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Flowers of Wet Grassland
Rivers and streams flow through many a wood and where the wood ends and open grassland or meadowland begins flowering
herbaceous plants grow in abundance and burst into flower every Spring and Summer. The grassland below is wet grassland.
Water is seeped into the soil from the nearby river and species particular to wet grassland are most abundant. Within this
meadow it is easy to recognise 6,7 or even more species of grass, such as the meadow foxtail (Alopecurus pratensis) with its
narrow conical head of flowers resembling a miniature fox's tail; smooth and rough meadow grasses (Poa pratensis and Poa
trivialis) with their radiating whorls of delicate flowers which are often a delicate purple in colour; cocksfoot (Dactylis glomerata),
tufted hair-grass (Deschampsia caespitosa), perennial rye grass (Lolium perenne) and meadow fescue (Festuca pratensis) - all
of which I have seen here, among others.
Rivers and streams flow through many a wood and where the wood ends and open grassland or meadowland begins flowering
herbaceous plants grow in abundance and burst into flower every Spring and Summer. The grassland below is wet grassland.
Water is seeped into the soil from the nearby river and species particular to wet grassland are most abundant. Within this
meadow it is easy to recognise 6,7 or even more species of grass, such as the meadow foxtail (Alopecurus pratensis) with its
narrow conical head of flowers resembling a miniature fox's tail; smooth and rough meadow grasses (Poa pratensis and Poa
trivialis) with their radiating whorls of delicate flowers which are often a delicate purple in colour; cocksfoot (Dactylis glomerata),
tufted hair-grass (Deschampsia caespitosa), perennial rye grass (Lolium perenne) and meadow fescue (Festuca pratensis) - all
of which I have seen here, among others.
The summer woodland is home to shade-tolerant flowers. In Spring, before the tree canopy has unfurled, less shade tolerant plants
like the bluebell (wild hyacinth) will grow and flower and are already turning to seed when the summer leaves of the overhead trees
open out and block much of the sunlight.
In late spring and summer, the woodland transforms in several obvious ways. Some trees put-out fantastic blossoms, especially the
cherry tree and horse chestnut tree (Aesculus hippocastanum). These showy flowers are intended to attract insects for pollination.
Some insects, like bees, have good colour vision as well as a good sense of smell and are attracted to these flowers both by their
scent and also by their colours. Insects generally have excellent ultraviolet vision, being capable of seeing colours that humans
cannot see and many flowers have ultraviolet markings that are intended to attract these insects and then direct them to the pollen
and nectaries. The flowers of the horse chestnut have inner yellow markings to guide their pollinators and once a flower is pollinated
the markings change to red, signalling to the insect that the flower is pollinated and so presents no nectar reward, thus guiding
insects to flowers awaiting pollination. Beneath the canopy with its new leaves that typically are a lush bright green when newly
formed (darkening as they mature) the forest floor springs into life with rapid growth. Tracks that are not in very frequent use rapidly
become overgrown with nettles and brambles. The brambles are scrambling, thorny shrubs, otherwise known as blackberries after
their autumn fruit. These brambles put out aerial shoots that actively swing about in very slow circling movements, seeking objects
for support which they will wrap around when their touch sensors are sufficiently activated by rubbing against the support. They also
put out creeping stems that snake across the forest floor, in slow motion, colonising new ground and finding supports to climb up or
scramble over. Brambles have pretty white or pink flowers.
Among nettles are the stinging nettles (Urtica dioica) and the dead nettles (archangels). Stinging nettles have tiny hollow glass hairs
or trichomes made of silica (one of the few obvious uses of silicon in plants). These hairs easily pierce the skin and snap when
brushed, releasing the formic acid (methanoic acid) that fills their hollow shafts into the skin, like hypodermic needles, and causing a
stinging sensation on the skin. (Presumable, the acid is drawn out of the broken 'needle' by capillary action). Dead nettles are
almost indistinguishable from stinging nettles, before they flower, but they do not sting. The flowers of stinging nettles are small
whitish flowers, born in rows on stalks that radiate in whorls at intervals along the stem. In contrast, the flowers of the archangel
(Lamium alba) are much larger, far fewer in number and easily seen as white zygomorphic flowers with orchid-like shapes.
like the bluebell (wild hyacinth) will grow and flower and are already turning to seed when the summer leaves of the overhead trees
open out and block much of the sunlight.
In late spring and summer, the woodland transforms in several obvious ways. Some trees put-out fantastic blossoms, especially the
cherry tree and horse chestnut tree (Aesculus hippocastanum). These showy flowers are intended to attract insects for pollination.
Some insects, like bees, have good colour vision as well as a good sense of smell and are attracted to these flowers both by their
scent and also by their colours. Insects generally have excellent ultraviolet vision, being capable of seeing colours that humans
cannot see and many flowers have ultraviolet markings that are intended to attract these insects and then direct them to the pollen
and nectaries. The flowers of the horse chestnut have inner yellow markings to guide their pollinators and once a flower is pollinated
the markings change to red, signalling to the insect that the flower is pollinated and so presents no nectar reward, thus guiding
insects to flowers awaiting pollination. Beneath the canopy with its new leaves that typically are a lush bright green when newly
formed (darkening as they mature) the forest floor springs into life with rapid growth. Tracks that are not in very frequent use rapidly
become overgrown with nettles and brambles. The brambles are scrambling, thorny shrubs, otherwise known as blackberries after
their autumn fruit. These brambles put out aerial shoots that actively swing about in very slow circling movements, seeking objects
for support which they will wrap around when their touch sensors are sufficiently activated by rubbing against the support. They also
put out creeping stems that snake across the forest floor, in slow motion, colonising new ground and finding supports to climb up or
scramble over. Brambles have pretty white or pink flowers.
Among nettles are the stinging nettles (Urtica dioica) and the dead nettles (archangels). Stinging nettles have tiny hollow glass hairs
or trichomes made of silica (one of the few obvious uses of silicon in plants). These hairs easily pierce the skin and snap when
brushed, releasing the formic acid (methanoic acid) that fills their hollow shafts into the skin, like hypodermic needles, and causing a
stinging sensation on the skin. (Presumable, the acid is drawn out of the broken 'needle' by capillary action). Dead nettles are
almost indistinguishable from stinging nettles, before they flower, but they do not sting. The flowers of stinging nettles are small
whitish flowers, born in rows on stalks that radiate in whorls at intervals along the stem. In contrast, the flowers of the archangel
(Lamium alba) are much larger, far fewer in number and easily seen as white zygomorphic flowers with orchid-like shapes.
| Flowers of Woodland and Meadows |
Above: even in this busy photo it is easy to identify three or four distinctly different grass species. A
plantain can also be seen in the foreground. It is here that grasses come into their own. If one lives in a city,
then it is easy to think of grass as simply a lush green cushion, pleasant for recreation, but otherwise
non-distinct. If one lives on or near to arable land then it is easy to think of grass as only a few cultivated
varieties of cereal. Wild grasses, however, are beautiful plants when in flower and when setting seed. The
diversity in grass flowers makes it strike home how many different species of grass there are.
Near to a nearby pond you will find other types of wetland grasses that prefer even wetter soil. Reeds, with
their tough hollow stems and beautiful flower-heads and the common rush (Juncus conglomeratus) with its
quite showy reddish flower clusters with a stem-like spathe above the inflorescence (making it appear as if
the flowers are borne half-way up the stem).
plantain can also be seen in the foreground. It is here that grasses come into their own. If one lives in a city,
then it is easy to think of grass as simply a lush green cushion, pleasant for recreation, but otherwise
non-distinct. If one lives on or near to arable land then it is easy to think of grass as only a few cultivated
varieties of cereal. Wild grasses, however, are beautiful plants when in flower and when setting seed. The
diversity in grass flowers makes it strike home how many different species of grass there are.
Near to a nearby pond you will find other types of wetland grasses that prefer even wetter soil. Reeds, with
their tough hollow stems and beautiful flower-heads and the common rush (Juncus conglomeratus) with its
quite showy reddish flower clusters with a stem-like spathe above the inflorescence (making it appear as if
the flowers are borne half-way up the stem).
Flowering plants belong to the Angiosperm group of plants. These include flowering herbs, shrubs and trees as well as grasses.
Conifers and yew trees are non-flowering and belong to the Gymnosperms (though sometimes the unfertilised cones of conifers
are referred to as 'flowers'). Gymnosperms do not completely enclose their seeds inside fruit, as the angiosperms do. Instead,
seeds are borne directly ion the scales of the female cones in conifers and partially enclosed by a fleshy aril in yew trees. Ferns,
horsetails and mosses produce neither flowers, seeds or fruit, but reproduce by naked spores.
Wind-pollinated flowers are non-scented and usually much smaller and less colourful, often greenish in colour, since they do not
need to attract insects. Wind-pollinated trees often bear clusters of flowers on catkins. Scales on the catkin seal the openings
shut when the catkin dangles motionless, but should the wind wave it about, then gaps in the tiny scale appear and the pollen
escapes to be carried away on the wind.
Wind-pollinated trees include: oak, beech, birch, ash, hornbeam, alder, elm and hazel.
Animal-pollinated trees and woody plants include: lime, hawthorn, box, cherry, apple, pear, elder, blackthorn and broom.
The distinction is not clear-cut. Some plants edge their bets, willow, for example, produces very visible catkins that can be
wind-pollinated, but are often pollinated by blue tits. The catkins produce copious amounts of nectar to feed the blue tits, an
expensive investment, which is offset by the fact that blue tits can carry a lot of pollen and travel large distances, each pollinating
many trees.
Other larger animals that may pollinate trees include bats, which in the tropics pollinate kapok, balsa, durian and baobab trees.
Birds, rodents and primates may also pollinate trees and the giraffe pollinates the knobthorn acacia (Acacia nigrescens) upon
whose leaves it feeds. Bird-pollinated plants often produce red hanging flowers. Flowers pollinated by flies, like arum, are typically
pale and dull. Bee pollinated flowers are often yellow or blue and flowers pollinated by moths and butterflies can have various
colours. The cocoa tree is pollinated by biting midges that breed in decaying cocoa pods.
Separation of the Sexes
Many plants have so-called perfect flowers, which are hermaphrodite with both male and female parts. Woody plants with
perfect flowers include limes, blackthorn, broom, cherries, apple, pear, privet, elms, elder, hawthorns, horse chestnuts,
whitebeams and some maples.
When the sexes are separate, then the plant may be monoecious (exhibit monoecy) or dioecious (exhibit dioecy). Monoecy is
more common in trees and is when separate male and female flowers occur on the same plant, e.g. sweet chestnut (Castanea
sativa), alder, beech, birches, box, hazel, hornbeam and oak. Monoecious conifers have separate male and female cones, e.g.
pines, cypresses, redwoods (separate male and female cones).
Dioecy is less common in trees, and occurs when separate male and female trees are found, and is found in holly (Ilex
aquifolium, though sometimes perfect flowers are found in holly), willows (rarely monoecious), juniper, poplars (rarely
monoecious), ash (sometimes mixed) and yew. In ash and yew, male and female flowers sometimes occur on the same tree.
Conifers and yew trees are non-flowering and belong to the Gymnosperms (though sometimes the unfertilised cones of conifers
are referred to as 'flowers'). Gymnosperms do not completely enclose their seeds inside fruit, as the angiosperms do. Instead,
seeds are borne directly ion the scales of the female cones in conifers and partially enclosed by a fleshy aril in yew trees. Ferns,
horsetails and mosses produce neither flowers, seeds or fruit, but reproduce by naked spores.
Wind-pollinated flowers are non-scented and usually much smaller and less colourful, often greenish in colour, since they do not
need to attract insects. Wind-pollinated trees often bear clusters of flowers on catkins. Scales on the catkin seal the openings
shut when the catkin dangles motionless, but should the wind wave it about, then gaps in the tiny scale appear and the pollen
escapes to be carried away on the wind.
Wind-pollinated trees include: oak, beech, birch, ash, hornbeam, alder, elm and hazel.
Animal-pollinated trees and woody plants include: lime, hawthorn, box, cherry, apple, pear, elder, blackthorn and broom.
The distinction is not clear-cut. Some plants edge their bets, willow, for example, produces very visible catkins that can be
wind-pollinated, but are often pollinated by blue tits. The catkins produce copious amounts of nectar to feed the blue tits, an
expensive investment, which is offset by the fact that blue tits can carry a lot of pollen and travel large distances, each pollinating
many trees.
Other larger animals that may pollinate trees include bats, which in the tropics pollinate kapok, balsa, durian and baobab trees.
Birds, rodents and primates may also pollinate trees and the giraffe pollinates the knobthorn acacia (Acacia nigrescens) upon
whose leaves it feeds. Bird-pollinated plants often produce red hanging flowers. Flowers pollinated by flies, like arum, are typically
pale and dull. Bee pollinated flowers are often yellow or blue and flowers pollinated by moths and butterflies can have various
colours. The cocoa tree is pollinated by biting midges that breed in decaying cocoa pods.
Separation of the Sexes
Many plants have so-called perfect flowers, which are hermaphrodite with both male and female parts. Woody plants with
perfect flowers include limes, blackthorn, broom, cherries, apple, pear, privet, elms, elder, hawthorns, horse chestnuts,
whitebeams and some maples.
When the sexes are separate, then the plant may be monoecious (exhibit monoecy) or dioecious (exhibit dioecy). Monoecy is
more common in trees and is when separate male and female flowers occur on the same plant, e.g. sweet chestnut (Castanea
sativa), alder, beech, birches, box, hazel, hornbeam and oak. Monoecious conifers have separate male and female cones, e.g.
pines, cypresses, redwoods (separate male and female cones).
Dioecy is less common in trees, and occurs when separate male and female trees are found, and is found in holly (Ilex
aquifolium, though sometimes perfect flowers are found in holly), willows (rarely monoecious), juniper, poplars (rarely
monoecious), ash (sometimes mixed) and yew. In ash and yew, male and female flowers sometimes occur on the same tree.
Click on the model of the passion
flower (left) for a biological description
of flower structure and function.
flower (left) for a biological description
of flower structure and function.
Left: The wild arum, Arum maculatum, is a remarkable
woodland flower that flowers in Spring and produces its
stalked columns of red berries in early summer. It belongs to
the arum lily family (Araceae). The leaves are large and
shaped like arrow-heads and often bear dark spots. The
'flower' (actually a structure around several flowers)
comprises a reddish-purple cylindrical structure, called the
spadix, borne on a stalk that descends into the basal bulb of
the flower. Behind the spadix is a large hood or spathe,
formed from a modified leaf. This stately appearance
probably led to their common name of Lords and Ladies.
They also have a common name of Cuckoo Pint (though they
have no relationship to cuckoos!). The flowers are large, but
easily overlooked due to their greenish colour and the fact
that they do not flower for long.
The size of the arum flower suggests that it is insect
pollinated, but its dull colour would not be suitable for bees
and butterflies. Instead, the arum attracts flies to pollinate it.
The spadix generates heat, maintaining its temperature at
several degrees above ambient. It also releases perfume that
smells of decay (some say it smells of excrement, others that
it smells of rotting meat and this probably depends on the
species of Arum). The heat of the spadix helps to volatilise
the odour substances. These substances consist largely of
ammonia and amines. The rotting smell attracts flies that land
to find the inside of the spathe very slippery and they fall
down into the bulb. The epidermal cells on the inner surface
of the spathe each have a minute papilla (wart-like
projection) which is soft, springy and slopes downwards.
Their are very few stomata on this inner surface, keeping the
surface otherwise smooth. This epidermis also carries
numerous tiny droplets of slippery oil. The downward pointing
papillae and oil droplets make it very hard for any insect to
retain a purchase. A mesh of stiff hairs filter out the largest
insects, who fall no further and can escape, but those of the
right size fall through into the bulb.
woodland flower that flowers in Spring and produces its
stalked columns of red berries in early summer. It belongs to
the arum lily family (Araceae). The leaves are large and
shaped like arrow-heads and often bear dark spots. The
'flower' (actually a structure around several flowers)
comprises a reddish-purple cylindrical structure, called the
spadix, borne on a stalk that descends into the basal bulb of
the flower. Behind the spadix is a large hood or spathe,
formed from a modified leaf. This stately appearance
probably led to their common name of Lords and Ladies.
They also have a common name of Cuckoo Pint (though they
have no relationship to cuckoos!). The flowers are large, but
easily overlooked due to their greenish colour and the fact
that they do not flower for long.
The size of the arum flower suggests that it is insect
pollinated, but its dull colour would not be suitable for bees
and butterflies. Instead, the arum attracts flies to pollinate it.
The spadix generates heat, maintaining its temperature at
several degrees above ambient. It also releases perfume that
smells of decay (some say it smells of excrement, others that
it smells of rotting meat and this probably depends on the
species of Arum). The heat of the spadix helps to volatilise
the odour substances. These substances consist largely of
ammonia and amines. The rotting smell attracts flies that land
to find the inside of the spathe very slippery and they fall
down into the bulb. The epidermal cells on the inner surface
of the spathe each have a minute papilla (wart-like
projection) which is soft, springy and slopes downwards.
Their are very few stomata on this inner surface, keeping the
surface otherwise smooth. This epidermis also carries
numerous tiny droplets of slippery oil. The downward pointing
papillae and oil droplets make it very hard for any insect to
retain a purchase. A mesh of stiff hairs filter out the largest
insects, who fall no further and can escape, but those of the
right size fall through into the bulb.
Inside the bulb, the inner wall has numerous tiny channels or air spaces, that connect to stomata in the outer surface. This
provides the inside of the bulb with air for the trapped insects. The lower part of the bulb has no papillae or oil droplets and the
trapped insects are free to walk around and over the female flowers clustered at the base of the bulb. Thus, any pollen they carry
from another flower of the same species may pollinate the female flowers. The male flowers are not yet shedding pollen, so
self-pollination is avoided. When the flower is ready, it releases its odour, from the tip of the spadix, most strongly at sunrise, as
soon as the air begins to warm. The smaller dung-feeding insects that slip inside the hood cannot get airborne quickly enough to
escape (larger flies may succeed in flying away and are in any case prevented from entering the bulb by the hairs). The hairs
over the bulb entrance are oily and slippery at this stage and those insects small enough slip through. Contrary to some claims,
the insects are generally never observed to deflect the hairs or walk into the bulb. The spacing between the hairs varies from
plant to plants, so that the maximum size of insect allowed to enter also varies. No insect is released before nightfall. The wall and
central column are too slippery to allow insects to escape. Insects may attempt to fly away from a dark chamber, such as a
darkened room or cave, when they can see a daylight opening and have enough space to deploy their wings. The bulb, with its
various internal organs has insufficient room and the hood blocks the sight of direct daylight above. Indeed, illumination of the
bulb, at least in some arums, comes predominantly from below, tempting the insects to seek an exit below, where there is none.
The insect guests are looked after to some degree, the female flowers secrete water and some organic foodstuffs, and humidity
within the bulb is high and the bulb is also ventilated. However, some insects do die inside the bulb and the insects seek to
escape. In at least one arum lily studied (Sauromatum) heat production occurred in the floral bulb at night. This presumably keeps
the pollinators warm, and active as they effect pollination. On the morning of the second day, the odour is much reduced. The
bulb and hood remain unclimbable, but the axis bearing the spathe has become climbable, as its surface cells have crumpled.
The insects climb the spadix and escape. On their way out, however, they must climb past the male flowers, which are now ripe,
picking up pollen on their way out. Should they become trapped by another Arum, then they may pollinate it. As arums set seed
quite readily, clearly many hapless insects get caught more than once!
The development of the spadix in arum lilies has been shown to be under the control of the phytohormone salicylic acid. This
hormone is produced by the stamen-bearing flowers as they develop on the spadix and triggers heat production (thermogenesis),
odour secretion and unfolding of the spathe. Thermogenesis occurs when the mitochondria inside the cells (organelles that
oxidise foodstuff fuels to release energy) switch from producing ATP (an 'energy storage' molecule) as they do in normal aerobic
respiration, to generating heat instead. They consume starch fuel reserves inside the spadix in order to generate this heat and
the starch content of the spadix decreases from about 32% of the dry mass of the spadix to only 6% after 8-10 hours of
thermogenesis. The starch is broken down into glucose and the glucose oxidised to liberate the heat. Oxygen is needed to oxidise
the glucose and during thermogenesis the rate of oxygen consumption by the spadix reaches a rate equivalent to the oxygen
consumption of a flying hummingbird!
provides the inside of the bulb with air for the trapped insects. The lower part of the bulb has no papillae or oil droplets and the
trapped insects are free to walk around and over the female flowers clustered at the base of the bulb. Thus, any pollen they carry
from another flower of the same species may pollinate the female flowers. The male flowers are not yet shedding pollen, so
self-pollination is avoided. When the flower is ready, it releases its odour, from the tip of the spadix, most strongly at sunrise, as
soon as the air begins to warm. The smaller dung-feeding insects that slip inside the hood cannot get airborne quickly enough to
escape (larger flies may succeed in flying away and are in any case prevented from entering the bulb by the hairs). The hairs
over the bulb entrance are oily and slippery at this stage and those insects small enough slip through. Contrary to some claims,
the insects are generally never observed to deflect the hairs or walk into the bulb. The spacing between the hairs varies from
plant to plants, so that the maximum size of insect allowed to enter also varies. No insect is released before nightfall. The wall and
central column are too slippery to allow insects to escape. Insects may attempt to fly away from a dark chamber, such as a
darkened room or cave, when they can see a daylight opening and have enough space to deploy their wings. The bulb, with its
various internal organs has insufficient room and the hood blocks the sight of direct daylight above. Indeed, illumination of the
bulb, at least in some arums, comes predominantly from below, tempting the insects to seek an exit below, where there is none.
The insect guests are looked after to some degree, the female flowers secrete water and some organic foodstuffs, and humidity
within the bulb is high and the bulb is also ventilated. However, some insects do die inside the bulb and the insects seek to
escape. In at least one arum lily studied (Sauromatum) heat production occurred in the floral bulb at night. This presumably keeps
the pollinators warm, and active as they effect pollination. On the morning of the second day, the odour is much reduced. The
bulb and hood remain unclimbable, but the axis bearing the spathe has become climbable, as its surface cells have crumpled.
The insects climb the spadix and escape. On their way out, however, they must climb past the male flowers, which are now ripe,
picking up pollen on their way out. Should they become trapped by another Arum, then they may pollinate it. As arums set seed
quite readily, clearly many hapless insects get caught more than once!
The development of the spadix in arum lilies has been shown to be under the control of the phytohormone salicylic acid. This
hormone is produced by the stamen-bearing flowers as they develop on the spadix and triggers heat production (thermogenesis),
odour secretion and unfolding of the spathe. Thermogenesis occurs when the mitochondria inside the cells (organelles that
oxidise foodstuff fuels to release energy) switch from producing ATP (an 'energy storage' molecule) as they do in normal aerobic
respiration, to generating heat instead. They consume starch fuel reserves inside the spadix in order to generate this heat and
the starch content of the spadix decreases from about 32% of the dry mass of the spadix to only 6% after 8-10 hours of
thermogenesis. The starch is broken down into glucose and the glucose oxidised to liberate the heat. Oxygen is needed to oxidise
the glucose and during thermogenesis the rate of oxygen consumption by the spadix reaches a rate equivalent to the oxygen
consumption of a flying hummingbird!
Grasses produce numerous small flowers, dull in
colour (though sometimes with reddish or purplish
or whitish tinge) and borne on long flexible stalks.
They produce copious amounts of pollen. All these
features favour wind-pollination. Although there are
woodland grasses, it is really in large open
windswept spaces where grasses dominate.
Grasses actively absorb silicon from the soil and
this is incorporated into silica (silicon dioxide)
crystals, often in specialised cells. Presumably, this
silica has a structural role, adding to the toughness
and hardness of grass tissues, along with the
strong fibres present in grass flower-stalks.
Strength is important in such long, thin and flexible
stalks that must remain upright for wind pollination.
colour (though sometimes with reddish or purplish
or whitish tinge) and borne on long flexible stalks.
They produce copious amounts of pollen. All these
features favour wind-pollination. Although there are
woodland grasses, it is really in large open
windswept spaces where grasses dominate.
Grasses actively absorb silicon from the soil and
this is incorporated into silica (silicon dioxide)
crystals, often in specialised cells. Presumably, this
silica has a structural role, adding to the toughness
and hardness of grass tissues, along with the
strong fibres present in grass flower-stalks.
Strength is important in such long, thin and flexible
stalks that must remain upright for wind pollination.
The red flower heads of Great Burnet (Sanguisorba officinalis) held atop stems up to one metre in length give
attractive clumps of colour to the meadow. They produce compound fruit (false fruit) containing a number of dry
achenes (dry fruit containing a single seed). Their extensive root system is good for holding soil together and
these plants are useful at removing toxins from the soil. Their leaves have been eaten as a salad vegetable.
Great Burnet grows in damp meadows.
attractive clumps of colour to the meadow. They produce compound fruit (false fruit) containing a number of dry
achenes (dry fruit containing a single seed). Their extensive root system is good for holding soil together and
these plants are useful at removing toxins from the soil. Their leaves have been eaten as a salad vegetable.
Great Burnet grows in damp meadows.
The Lady's Bedstraw (Galium verum) or Yellow Bedstraw prefers dry grassy places and clumps grow here in the drier
parts of these meadows. It's flowers are very soft and fluffy to the touch and this plant was used as bedding in the
Middle Ages, being dried and then used to stuff mattresses. This plant was also used for curdling milk when making
cheese and as a source of a yellow dye.
parts of these meadows. It's flowers are very soft and fluffy to the touch and this plant was used as bedding in the
Middle Ages, being dried and then used to stuff mattresses. This plant was also used for curdling milk when making
cheese and as a source of a yellow dye.
Above: a plantain (Plantago). The tall inflorescence springs from a rosette of leaves and bears many flowers clustered together in a spike. The flowers develop
first at the base of the spike and the female parts mature before the male parts (protogyny). The whorl of white hairlike tufts seen protruding in the specimen
above are the anthers of the mature male flowers. This separation in time, between the development of the female and male organs helps promote
cross-pollination. Even though plantains may exhibit genetic self-incompatibility (meaning that its own pollen grains will not germinate when in contact with the
female stigmas of the same plant, protogyny reduces pollen-pistil interference which occurs when the plant's own (incompatible) pollen clogs the stigmas,
reducing the likelihood that pollen from another plant will attach. (The pistil is the female part of the flower, comprising one or more carpels that may be fused
together). Plantains are wind-pollinated. The plantain above is the Ribwort Plantain (Plantago lanceolata) with its narrow leaves and blackish flower-heads.
Along the well-trodden paths leading to the meadow another species of plantain is found, Plantago major, the Greater Plantain, which has much longer,
narrower and greener flower-heads and broad leaves. (Good external link).
first at the base of the spike and the female parts mature before the male parts (protogyny). The whorl of white hairlike tufts seen protruding in the specimen
above are the anthers of the mature male flowers. This separation in time, between the development of the female and male organs helps promote
cross-pollination. Even though plantains may exhibit genetic self-incompatibility (meaning that its own pollen grains will not germinate when in contact with the
female stigmas of the same plant, protogyny reduces pollen-pistil interference which occurs when the plant's own (incompatible) pollen clogs the stigmas,
reducing the likelihood that pollen from another plant will attach. (The pistil is the female part of the flower, comprising one or more carpels that may be fused
together). Plantains are wind-pollinated. The plantain above is the Ribwort Plantain (Plantago lanceolata) with its narrow leaves and blackish flower-heads.
Along the well-trodden paths leading to the meadow another species of plantain is found, Plantago major, the Greater Plantain, which has much longer,
narrower and greener flower-heads and broad leaves. (Good external link).
Woodland Flowers
Below: bindweed with its large white
trumpet-shaped flowers.
Below: bindweed with its large white
trumpet-shaped flowers.
Left: Birdsfoot Trefoil, a small lotus flower of the
peaflower family. There are two species
commonly found in these habitats: Lotus
corniculatus and Lotus pedunculata (formerly
Lotus uliginosus). Lotus corniculatus has variable
flower colour, ranging from orange-red to yellow,
giving it its common name of Eggs and Bacon. In
particular the lower of the three petallate lobes,
the keel formed of two petals pressed together,
varies in colour according to temperature (this
being under both genetic and environmental
control). The sexual organs are beneath the keel
and the weight of a bee landing on the keel
springs it apart to reveal the sexual parts for
pollination. Dark coloured keels, those that are
orange-red, keep the sexual organs at a much
warmer temperature as they absorb more light
radiation. Presumably, this variation in colour
maintains the sexual organs at their optimum
temperature. These flowers are called 'birdsfoot'
because of the arrangement of the pea-like pods
that radiate from the inflorescence like the toes of
a bird's foot. Trefoil refers to the arrangement of
the leaves: each leaf has five leaflets, but two of
these are held back, so that the leaves appear to
be made of three leaflets each and so appear to
the casual observer like leaves arranged in
groups of three.
peaflower family. There are two species
commonly found in these habitats: Lotus
corniculatus and Lotus pedunculata (formerly
Lotus uliginosus). Lotus corniculatus has variable
flower colour, ranging from orange-red to yellow,
giving it its common name of Eggs and Bacon. In
particular the lower of the three petallate lobes,
the keel formed of two petals pressed together,
varies in colour according to temperature (this
being under both genetic and environmental
control). The sexual organs are beneath the keel
and the weight of a bee landing on the keel
springs it apart to reveal the sexual parts for
pollination. Dark coloured keels, those that are
orange-red, keep the sexual organs at a much
warmer temperature as they absorb more light
radiation. Presumably, this variation in colour
maintains the sexual organs at their optimum
temperature. These flowers are called 'birdsfoot'
because of the arrangement of the pea-like pods
that radiate from the inflorescence like the toes of
a bird's foot. Trefoil refers to the arrangement of
the leaves: each leaf has five leaflets, but two of
these are held back, so that the leaves appear to
be made of three leaflets each and so appear to
the casual observer like leaves arranged in
groups of three.
Left: the bulrush, Typha latifolia, or reedmace occurs at
the margins of ponds, lakes and rivers. Here it is beside a
pond in the meadow. The bulrush flower stem grows up
to 2.5 m tall and bears a cylindrical mass of brown female
flowers and above that a smaller mass of male flowers.
An average bulrush may produce a quarter of a million
seeds! It is one of the few brown flowers found in Britain.
Explore the pond.
Grasses have their enemies! Growing in this meadow is the Yellow Rattle or Hay Rattle, which is a hemiparasite (partial
parasite that also makes its own food by photosynthesis) that feeds on grasses. Its roots form junctions with grass roots, called
haustoria. In these junctions the xylem systems of the host and parasite interconnect and the parasite draws xylem sap,
containing water and minerals absorbed by the grass roots, into its own body. The Hay Rattle is good for the meadow, as it
keeps the grass in check and stops it from completely dominating and so increases biodiversity.
parasite that also makes its own food by photosynthesis) that feeds on grasses. Its roots form junctions with grass roots, called
haustoria. In these junctions the xylem systems of the host and parasite interconnect and the parasite draws xylem sap,
containing water and minerals absorbed by the grass roots, into its own body. The Hay Rattle is good for the meadow, as it
keeps the grass in check and stops it from completely dominating and so increases biodiversity.
Orchids
Left: this orchid, probably the Common Spotted Orchid,
Dactylorhiza fuchsii, is the only orchid flowering in
these meadows at present.
Orchids are extremely diverse plants with fascinating
habits and beautiful flowers. Most are tropical, and
tropical orchids can have especially fantastic flowers,
however, temperate orchids can also have
extraordinary, though often smaller, flowers.
Some orchids of the New World Tropics have
specialised pollinators, the orchid bees. These bees
are solitary and collect perfume (terpenes) produced
by the orchid. They have groups of absorbant hairs,
called mops, on the tarsi of their forelegs with which
they rub the orchid scent gland and about once a
minute, they stop rubbing, hover above the orchid and
wipe their foreleg mops against the metatarsi of their
middle legs, each of which is equipped with a ridge
bearing bristles that rake the scent droplets from the
mops. The hind legs contain the perfume storage
chambers (sponge chambers) on their tibia. The
openings of these chambers are brought into contact
with the rakes on the midlegs and hairs around the
openings wick up the scent and conduct it inside the
perfume chamber where it is taken up by a mass of
branching hairs inside, forming a sponge.
Left: this orchid, probably the Common Spotted Orchid,
Dactylorhiza fuchsii, is the only orchid flowering in
these meadows at present.
Orchids are extremely diverse plants with fascinating
habits and beautiful flowers. Most are tropical, and
tropical orchids can have especially fantastic flowers,
however, temperate orchids can also have
extraordinary, though often smaller, flowers.
Some orchids of the New World Tropics have
specialised pollinators, the orchid bees. These bees
are solitary and collect perfume (terpenes) produced
by the orchid. They have groups of absorbant hairs,
called mops, on the tarsi of their forelegs with which
they rub the orchid scent gland and about once a
minute, they stop rubbing, hover above the orchid and
wipe their foreleg mops against the metatarsi of their
middle legs, each of which is equipped with a ridge
bearing bristles that rake the scent droplets from the
mops. The hind legs contain the perfume storage
chambers (sponge chambers) on their tibia. The
openings of these chambers are brought into contact
with the rakes on the midlegs and hairs around the
openings wick up the scent and conduct it inside the
perfume chamber where it is taken up by a mass of
branching hairs inside, forming a sponge.
The diagram on the right shows a section through the
wall of a bean pod. The outermost layer is the
exocarp, made-up of the epidermis and a hypodermis
of tough sclerenchyma fibres. The middle layer, or
mesocarp, consists of soft, fleshy and green
parenchyma cells (containing chloropolasts with
chlorophyll). The inner layer is the endocarp,
consisting of several layers of tough sclerenchyma
fibres and an epidermis lining the inside of the pod.
Think of broad bean pods. Young pods are soft
enough to eat, but on the older pods it is easier just to
scrape away the soft parenchyma and epidermises
from each valve with your teeth, rather like eating an
artichoke leaf, and you will be left with a tough
sheet-like structure on the inside of the valve, which is
the sclerenchyma of the endocarp. Notice that the
fibres in the endocarp run more-or-less at right angles
to the sclerenchyma in the exocarp. The fibres will
contract along their length when they dry out, exerting
a pulling force, so those in the exocarp pull in a
different direction to those in the endocarp. This will
cause the two valves of the pod to twist and pull apart,
scattering their seeds with explosive force.
Furthermore, the cell walls of the sclerenchyma fibres
have helical; fibres within them, which wrap around the
axis of each cell like a spring and the pitch of these
helical springs within each layer of sclerenchyma is
different to those in the adjacent layers, so some
layers contract more than others. This also assists
with twisting and pulling apart the valves.
wall of a bean pod. The outermost layer is the
exocarp, made-up of the epidermis and a hypodermis
of tough sclerenchyma fibres. The middle layer, or
mesocarp, consists of soft, fleshy and green
parenchyma cells (containing chloropolasts with
chlorophyll). The inner layer is the endocarp,
consisting of several layers of tough sclerenchyma
fibres and an epidermis lining the inside of the pod.
Think of broad bean pods. Young pods are soft
enough to eat, but on the older pods it is easier just to
scrape away the soft parenchyma and epidermises
from each valve with your teeth, rather like eating an
artichoke leaf, and you will be left with a tough
sheet-like structure on the inside of the valve, which is
the sclerenchyma of the endocarp. Notice that the
fibres in the endocarp run more-or-less at right angles
to the sclerenchyma in the exocarp. The fibres will
contract along their length when they dry out, exerting
a pulling force, so those in the exocarp pull in a
different direction to those in the endocarp. This will
cause the two valves of the pod to twist and pull apart,
scattering their seeds with explosive force.
Furthermore, the cell walls of the sclerenchyma fibres
have helical; fibres within them, which wrap around the
axis of each cell like a spring and the pitch of these
helical springs within each layer of sclerenchyma is
different to those in the adjacent layers, so some
layers contract more than others. This also assists
with twisting and pulling apart the valves.
Above: a legume pod having dehisced
(dried-out) and opened.
(dried-out) and opened.
Above: a legume pod splits into two halves when it dries. The
vascular bundles are shown as dotted areas. Note that the
vascular bundle in the mid-vein is split into two when the pod
opens.
vascular bundles are shown as dotted areas. Note that the
vascular bundle in the mid-vein is split into two when the pod
opens.
The perfume seems to intoxicate the bees and may even be addictive! The orchid Gongora maculata is pollinated by the bee Euglossa cordata. The bee
becomes intoxicated and slips, falling into a chutelike structure in the flower, rear-end first. Its abdomen bumps a sticky disc (the viscidium) containing the pair
of pollen packets (pollinia, characteristic of orchids in which pollen is dispersed in packets) which therefore become stuck to the rear end of the bee. The
orchid Coryanthes speciosa has a similar shute that leads into a fluid-filled barrel, filled with fluid secreted by glands in the flower. A narrow tunnel is the only
escape route, and this takes the insect under the stigma, picking up any pollinia the bee might have from a previous flower visit, and then past the pollinia,
picking up more pollen. This flower wilts within hours of pollination.
The orchid Catesetum has a trigger mechanism which is activated when the pollinating insect lands on the flower, firing the pollinia attached to an adhesive disc
at the insect!
The Lady's Slipper Orchid, Cypripedium calceolus, is a temperate orchid which also occurs in Britain. This has a chute down which the pollinating insect slides.
The exit is a hairy path, giving the insect grip, which takes the insect under the stigma and an anther and is flanked by translucent spots or windows which guide
the insect (insects are often attracted to light when attempting to exit an enclosed space).
becomes intoxicated and slips, falling into a chutelike structure in the flower, rear-end first. Its abdomen bumps a sticky disc (the viscidium) containing the pair
of pollen packets (pollinia, characteristic of orchids in which pollen is dispersed in packets) which therefore become stuck to the rear end of the bee. The
orchid Coryanthes speciosa has a similar shute that leads into a fluid-filled barrel, filled with fluid secreted by glands in the flower. A narrow tunnel is the only
escape route, and this takes the insect under the stigma, picking up any pollinia the bee might have from a previous flower visit, and then past the pollinia,
picking up more pollen. This flower wilts within hours of pollination.
The orchid Catesetum has a trigger mechanism which is activated when the pollinating insect lands on the flower, firing the pollinia attached to an adhesive disc
at the insect!
The Lady's Slipper Orchid, Cypripedium calceolus, is a temperate orchid which also occurs in Britain. This has a chute down which the pollinating insect slides.
The exit is a hairy path, giving the insect grip, which takes the insect under the stigma and an anther and is flanked by translucent spots or windows which guide
the insect (insects are often attracted to light when attempting to exit an enclosed space).
Some orchid flowers mimic female insects, as in the Ophrys genus of orcghids,
found mostly in the Mediterranean, but some as far north as Norway. These
are pollinating by hymenopterans (bees and wasps). Each flower is a false
female, mimicking the female insect of its pollinator species in shape, colour,
texture (being hairy in the right places) and most importantly, in scent. These
orchids secrete molecules that mimic insect pheromones! Males of the
exploited insect species are attracted by the scent, identify with the colour,
size and shape of the false female and attempt to copulate - so-called
pseudocopulation in which the attempt is eventually aborted with release of
spermatophores (packets of sperm, the form in which sperm are released by
insects). By this time, however, the insect has already delivered any pollinia it
brought from another flower and picked up the flower's own pollinia. Clearly, in
order to work, the male must be fooled more than once by different flowers!
The insect receives no food or perfume reward, and is simply being exploited
by the orchid. Ophrys apifera, the bee orchid, found on mainland Europe is
pollinated by its exploited insect species, but in England its pollinator is absent
and there it self-pollinates.
Orchids also form interesting relations with fungi and plants. Like most
flowering plants, orchids rely on fungi associated with their roots (and forming
mycorhizae) to obtain sufficient nutrients from the soil. Orchid's produce small
seeds with few food reserves and their seedlings will not grow without a
suitable fungal partner, which 'infects' the orchid roots as soon as germination
takes place. In all other plants, the plant provides the fungus with organic
carbon obtained by photosynthesis, in return for soil minerals, such as
phosphorous. Orchid mycorhizae are the exception, in that the orchid also
draws organic carbon from the fungus, indeed transfer of nutrients from the
plant to the fungus is not observed - the orchid appears to be parasitising the
fungus! Indeed, whenever the fungus infects a cell in the orchid root, the part
of the fungus mycelium inside the cell is short-lived as it is soon digested by
the orchid, which is eating the fungus! Some of these fungi obtain their food
from rotting plant matter, others are parasites of other plants, including trees,
in which case the orchid is parasitising a parasite and effectively steeling
nutrients from the host tree! This allows some orchids to endure long periods
in shade, enabling them to fluorish beneath the dense canopies of beech
trees, which exclude so much light that few plants can thrive beneath them.
The bird's nest orchid is brown, lacking chlorophyll as it has no need to
photosynthesise, being totally dependent on its mycorhizal fungus, and can
grow in the most shaded beech woodlands.
found mostly in the Mediterranean, but some as far north as Norway. These
are pollinating by hymenopterans (bees and wasps). Each flower is a false
female, mimicking the female insect of its pollinator species in shape, colour,
texture (being hairy in the right places) and most importantly, in scent. These
orchids secrete molecules that mimic insect pheromones! Males of the
exploited insect species are attracted by the scent, identify with the colour,
size and shape of the false female and attempt to copulate - so-called
pseudocopulation in which the attempt is eventually aborted with release of
spermatophores (packets of sperm, the form in which sperm are released by
insects). By this time, however, the insect has already delivered any pollinia it
brought from another flower and picked up the flower's own pollinia. Clearly, in
order to work, the male must be fooled more than once by different flowers!
The insect receives no food or perfume reward, and is simply being exploited
by the orchid. Ophrys apifera, the bee orchid, found on mainland Europe is
pollinated by its exploited insect species, but in England its pollinator is absent
and there it self-pollinates.
Orchids also form interesting relations with fungi and plants. Like most
flowering plants, orchids rely on fungi associated with their roots (and forming
mycorhizae) to obtain sufficient nutrients from the soil. Orchid's produce small
seeds with few food reserves and their seedlings will not grow without a
suitable fungal partner, which 'infects' the orchid roots as soon as germination
takes place. In all other plants, the plant provides the fungus with organic
carbon obtained by photosynthesis, in return for soil minerals, such as
phosphorous. Orchid mycorhizae are the exception, in that the orchid also
draws organic carbon from the fungus, indeed transfer of nutrients from the
plant to the fungus is not observed - the orchid appears to be parasitising the
fungus! Indeed, whenever the fungus infects a cell in the orchid root, the part
of the fungus mycelium inside the cell is short-lived as it is soon digested by
the orchid, which is eating the fungus! Some of these fungi obtain their food
from rotting plant matter, others are parasites of other plants, including trees,
in which case the orchid is parasitising a parasite and effectively steeling
nutrients from the host tree! This allows some orchids to endure long periods
in shade, enabling them to fluorish beneath the dense canopies of beech
trees, which exclude so much light that few plants can thrive beneath them.
The bird's nest orchid is brown, lacking chlorophyll as it has no need to
photosynthesise, being totally dependent on its mycorhizal fungus, and can
grow in the most shaded beech woodlands.
Above: The Indian Balsam (Himalyan Balsam, Policeman's Helmet) Impatiens glandulifera. This
tall plant, with its exotic looking flowers, was introduced to Britain from Asian in 1839 and
subsequently escaped from greenhouses to become naturalised. It's flowers vary from white, to
pink, to purple and form capsular fruit, the capsules exploding when dry, throwing seeds about 2
metres from the plant. Each capsule produces 4-12 seeds and an average plant produces some
800 seeds. Indian Balsam is a common wetland plant.
tall plant, with its exotic looking flowers, was introduced to Britain from Asian in 1839 and
subsequently escaped from greenhouses to become naturalised. It's flowers vary from white, to
pink, to purple and form capsular fruit, the capsules exploding when dry, throwing seeds about 2
metres from the plant. Each capsule produces 4-12 seeds and an average plant produces some
800 seeds. Indian Balsam is a common wetland plant.
Above: thistles with their spiny leaves are abundant in clumps around the
edges of the meadows. These are composites, like daisies, in which each
apparent 'petal' is actually a small flower. I also found a stemless
knapweed nearby, growing low to the ground (probably Carduncellus
mitissimus) and a week later, more knapweeds were in flower.
Knapweeds are similar to thistles, but their leaves are less spiky. The
fruit are very fluffy and silky and easily carried off by the wind.
edges of the meadows. These are composites, like daisies, in which each
apparent 'petal' is actually a small flower. I also found a stemless
knapweed nearby, growing low to the ground (probably Carduncellus
mitissimus) and a week later, more knapweeds were in flower.
Knapweeds are similar to thistles, but their leaves are less spiky. The
fruit are very fluffy and silky and easily carried off by the wind.
In the close-up of a Great Burnet flower head above, the individual flowers that make
up the head can be easily seen.
up the head can be easily seen.
The Indian Balsam is a large annual plant. Flowering herbs (herb = non-woody plant) can be annual, living and flowering only for a single
season, biennial or perennial. Perennials flower each year and may die-back above ground completely over the winter, surviving as
underground storage organs, such as bulbs and rhizomes (both types of underground stem) which store nutrients. These stems store
nutrients for growth of new shoots the following year, during which time photosynthesis by the new shoots will replenish the underground
storage organs ready for next year. Orchids are perennial and have a pair of bulbs beneath the soil, one old and depleted and one new and
replete with nutrients. This is how they derive their name, 'orchid' literally means 'testicle plant'. Great Burnet is also perennial, as is the
bluebell (grows from a bulb and flowers in spring), Birdsfoot Trefoil, the Ribwort Plantain, and the Cuckoo Pint (growing from a rhizome).
Grasses may be annual or perennial (forming rhizomes).
season, biennial or perennial. Perennials flower each year and may die-back above ground completely over the winter, surviving as
underground storage organs, such as bulbs and rhizomes (both types of underground stem) which store nutrients. These stems store
nutrients for growth of new shoots the following year, during which time photosynthesis by the new shoots will replenish the underground
storage organs ready for next year. Orchids are perennial and have a pair of bulbs beneath the soil, one old and depleted and one new and
replete with nutrients. This is how they derive their name, 'orchid' literally means 'testicle plant'. Great Burnet is also perennial, as is the
bluebell (grows from a bulb and flowers in spring), Birdsfoot Trefoil, the Ribwort Plantain, and the Cuckoo Pint (growing from a rhizome).
Grasses may be annual or perennial (forming rhizomes).
Above: a grass flower-head (with trefoil in the background).
Grass flowers are arranged in spikes, each spike being carried on a peduncle
(stalk). A number of spikes may be attached to a single inflorescence.
(stalk). A number of spikes may be attached to a single inflorescence.
Conveniently, the flowers are also arranged in three distinct parts, the lower keel and the two wings. Being members of the pea-family, the trefoils
are legumes and so their roots develop nodules, especially in nitrogen-poor soil, that contain a symbiotic bacterium, Rhizobium, which 'fixes'
nitrogen, that is it takes atmospheric nitrogen gas and converts it into compounds of nitrogen that the plant can use as building blocks for
nitrogen-containing molecules (principally amino acids which make proteins and nucleotides which make the nucleic acids DNA and RNA).
Another member of the peaflower family found in these meadows is clover, both white clover (Trifolium repens) and red clover (Trifolium pratense).
These too are capable of fixing nitrogen in root-nodules and are also sometimes called 'trefoil' because of their leaves which are divided into three
leaflets, this name is given especially to yellow clovers. The head of the clover is a cluster of small tube-like flowers (each flower looking like a
petal). These narrow floral tubes restrict the types of pollinators that can access the nectar and pollen. White clovers, with their smaller more
spherical flower-heads, have shorter tubes, short enough for the honey bee to reach with its short 'tongue' or proboscis. The honeybee cannot
reach the nectaries of the red clover which has longer floral tubes. Red clover is pollinated by bumble bees, which have longer 'tongues'.
Honeybees reside in hedges and woods and meadows next to suitable bumble bee habitats produce much more seed. The white clover, however,
is good food for honeybees and hence suited for honey production. The robber bumble bee cheats, it makes a hole in the base of the red clover
floret to suck out the nectar without pollinating the flower!
In addition to nitrogen fixation, legumes have characteristic fruit - pods. Each pod is a single carpel with a single internal locule (cavity) formed, in
evolutionary terms, by a single leaf folding over upon itself, and enclosing several ovules within, which become the seeds after fertilisation.
Characteristic of these pods is their mechanism of seed dispersal. As the pod dries, it suddenly violently ruptures, sending the seeds flying. To
understand how this happens, look at the structure of the pod (carpel) wall for a typical bean pod, shown below:
are legumes and so their roots develop nodules, especially in nitrogen-poor soil, that contain a symbiotic bacterium, Rhizobium, which 'fixes'
nitrogen, that is it takes atmospheric nitrogen gas and converts it into compounds of nitrogen that the plant can use as building blocks for
nitrogen-containing molecules (principally amino acids which make proteins and nucleotides which make the nucleic acids DNA and RNA).
Another member of the peaflower family found in these meadows is clover, both white clover (Trifolium repens) and red clover (Trifolium pratense).
These too are capable of fixing nitrogen in root-nodules and are also sometimes called 'trefoil' because of their leaves which are divided into three
leaflets, this name is given especially to yellow clovers. The head of the clover is a cluster of small tube-like flowers (each flower looking like a
petal). These narrow floral tubes restrict the types of pollinators that can access the nectar and pollen. White clovers, with their smaller more
spherical flower-heads, have shorter tubes, short enough for the honey bee to reach with its short 'tongue' or proboscis. The honeybee cannot
reach the nectaries of the red clover which has longer floral tubes. Red clover is pollinated by bumble bees, which have longer 'tongues'.
Honeybees reside in hedges and woods and meadows next to suitable bumble bee habitats produce much more seed. The white clover, however,
is good food for honeybees and hence suited for honey production. The robber bumble bee cheats, it makes a hole in the base of the red clover
floret to suck out the nectar without pollinating the flower!
In addition to nitrogen fixation, legumes have characteristic fruit - pods. Each pod is a single carpel with a single internal locule (cavity) formed, in
evolutionary terms, by a single leaf folding over upon itself, and enclosing several ovules within, which become the seeds after fertilisation.
Characteristic of these pods is their mechanism of seed dispersal. As the pod dries, it suddenly violently ruptures, sending the seeds flying. To
understand how this happens, look at the structure of the pod (carpel) wall for a typical bean pod, shown below:
Seed Dispersal in Legumes
Pollination in Arum
Click on the image above to enlarge it and see how many different grass
species you can find.
species you can find.
The photos above depict these meadows in June/July. However, earlier in the year, around April/May these meadows were yellow, not with
pea flowers, but with cowslips (Primula veris) a type of primrose. Primroses have an interesting mechanism to reduce self-pollination and
enhance cross-pollination, meaning that they are designed to be pollinated most easily by pollen from a different plant. Cross-pollination
prevents 'in-breeding' and maintains genetic diversity in a population, which also helps to counteract the effects of detrimental mutations in
genes, since with cross-breeding, an organism is more likely to inherit a healthy copy of a gene if its parent population contains faulty copies.
Primrose flowers, even on the same plant, come in two morphological varieties: pine-eyed and thrum-eyed. pin-eyed are so-called because
the carpel has a long style that raises the stigma to the top of the floral tube, where it is visible from above as a 'pin-eye' like structure. In a
pin-eyed flower the stamens are lower down than the stigma in the floral tube. In thrum-eyed flowers, the style is shorter and the stamens
higher, so that the stigma is far beneath the stamens. Pollen must travel from a stamen to a stigma, and attach to the stigma, to effect
pollination.
pea flowers, but with cowslips (Primula veris) a type of primrose. Primroses have an interesting mechanism to reduce self-pollination and
enhance cross-pollination, meaning that they are designed to be pollinated most easily by pollen from a different plant. Cross-pollination
prevents 'in-breeding' and maintains genetic diversity in a population, which also helps to counteract the effects of detrimental mutations in
genes, since with cross-breeding, an organism is more likely to inherit a healthy copy of a gene if its parent population contains faulty copies.
Primrose flowers, even on the same plant, come in two morphological varieties: pine-eyed and thrum-eyed. pin-eyed are so-called because
the carpel has a long style that raises the stigma to the top of the floral tube, where it is visible from above as a 'pin-eye' like structure. In a
pin-eyed flower the stamens are lower down than the stigma in the floral tube. In thrum-eyed flowers, the style is shorter and the stamens
higher, so that the stigma is far beneath the stamens. Pollen must travel from a stamen to a stigma, and attach to the stigma, to effect
pollination.
Pin-eyed primrose.
Thrum-eyed primrose.
If an insect with a long proboscis visits a pin-eye flower and reaches for the nectar at the base of the floral tube, then pollen
will rub onto its proboscis. If this same insect then visits a thrum-eye flower, then the pollen is at the right height to rub off
onto the short stigma of the thrum-eye flower. The insect's head will also become covered with pollen from the thrum-eye
flower. If this insect now returns to a pin-eye flower then the pollen on its head will be at the correct height to rub off onto
the stigma of the pin-eye flower.
will rub onto its proboscis. If this same insect then visits a thrum-eye flower, then the pollen is at the right height to rub off
onto the short stigma of the thrum-eye flower. The insect's head will also become covered with pollen from the thrum-eye
flower. If this insect now returns to a pin-eye flower then the pollen on its head will be at the correct height to rub off onto
the stigma of the pin-eye flower.
Bibliography/References
Insects and Flowers, The biology of a partnership. F.G. Barth, 1991. Princeton University Press.
Floral Aroma: How Far Will Plants Go to Attract Pollinators? David C. Robacker, Bastiaan J. D. Meeuse, Eric H. BioScience,
Vol. 38, No. 6 (Jun., 1988), pp. 390-398.
Dynamics of Thermogenesis and Structure of Epidermal Tissues in Inflorescences of Arum maculatum. Edith
Bermadinger-Stabentheiner and Anton Stabentheiner. New Phytologist, Vol. 131, No. 1 (Sep., 1995), pp. 41-50.
The Truth About Pollination in Arum. K. J. DormerSource: New Phytologist, Vol. 59, No. 3 (Dec., 1960), pp. 298-301.
Arum Maculatum L. F. A. Sowter. Journal of Ecology, Vol. 37, No. 1 (Jul., 1949), pp. 207-219.
The Keel Colour Polymorphism in Lotus corniculatus L.: Differences in Internal Flower Temperatures. Jennifer Jewell, Juno
McKee, A. J. Richards. New Phytologist, Vol. 128, No. 2 (Oct., 1994), pp. 363-368.
Lotus Corniculatus L. David A. Jones and Roy Turkington. Journal of Ecology, Vol. 74, No. 4 (Dec., 1986), pp. 1185-1212.
Chemical Defense Production in Lotus corniculatus L. I. The Effects of Nitrogen Source onGrowth, Reproduction and
Defense. Michelle A. Briggs. Oecologia, Vol. 83, No. 1 (1990), pp. 27-31.
The Endosperm-Embryo Relationship in an Autonomous Apomict, Taraxacum officinale. D. C. Cooper and R. A. Brink.
Botanical Gazette, Vol. 111, No. 2 (Dec., 1949), pp. 139-153.
Clonal Variation in Floral Stage Timing in the Common Dandelion Taraxacum officinale (Asteraceae). Matthew H. Collier
and Steven H. Rogstad. American Journal of Botany, Vol. 91, No. 11 (Nov., 2004), pp. 1828-1833.
Wild Flowers by Colour, The easy way to flower identification. M. Blamey, 1977. Dorling Kindersley.
Wild Flowers. Collins GEM Guides. M. Blamey, R. Fitter, 1980. Collins.
The Living countryside
Insects and Flowers, The biology of a partnership. F.G. Barth, 1991. Princeton University Press.
Floral Aroma: How Far Will Plants Go to Attract Pollinators? David C. Robacker, Bastiaan J. D. Meeuse, Eric H. BioScience,
Vol. 38, No. 6 (Jun., 1988), pp. 390-398.
Dynamics of Thermogenesis and Structure of Epidermal Tissues in Inflorescences of Arum maculatum. Edith
Bermadinger-Stabentheiner and Anton Stabentheiner. New Phytologist, Vol. 131, No. 1 (Sep., 1995), pp. 41-50.
The Truth About Pollination in Arum. K. J. DormerSource: New Phytologist, Vol. 59, No. 3 (Dec., 1960), pp. 298-301.
Arum Maculatum L. F. A. Sowter. Journal of Ecology, Vol. 37, No. 1 (Jul., 1949), pp. 207-219.
The Keel Colour Polymorphism in Lotus corniculatus L.: Differences in Internal Flower Temperatures. Jennifer Jewell, Juno
McKee, A. J. Richards. New Phytologist, Vol. 128, No. 2 (Oct., 1994), pp. 363-368.
Lotus Corniculatus L. David A. Jones and Roy Turkington. Journal of Ecology, Vol. 74, No. 4 (Dec., 1986), pp. 1185-1212.
Chemical Defense Production in Lotus corniculatus L. I. The Effects of Nitrogen Source onGrowth, Reproduction and
Defense. Michelle A. Briggs. Oecologia, Vol. 83, No. 1 (1990), pp. 27-31.
The Endosperm-Embryo Relationship in an Autonomous Apomict, Taraxacum officinale. D. C. Cooper and R. A. Brink.
Botanical Gazette, Vol. 111, No. 2 (Dec., 1949), pp. 139-153.
Clonal Variation in Floral Stage Timing in the Common Dandelion Taraxacum officinale (Asteraceae). Matthew H. Collier
and Steven H. Rogstad. American Journal of Botany, Vol. 91, No. 11 (Nov., 2004), pp. 1828-1833.
Wild Flowers by Colour, The easy way to flower identification. M. Blamey, 1977. Dorling Kindersley.
Wild Flowers. Collins GEM Guides. M. Blamey, R. Fitter, 1980. Collins.
The Living countryside
Above: Knapweeds.
Grass flowers have the classic
morphology of wind-pollinated flowers.
The petals are small and lack special
colouring, the long feathery stigmas have
a lot of surface area with which to catch
pollen and the stamens hang down on
long flexible filaments, so that they are
easily shaken about by the wind,
shedding their pollen.
morphology of wind-pollinated flowers.
The petals are small and lack special
colouring, the long feathery stigmas have
a lot of surface area with which to catch
pollen and the stamens hang down on
long flexible filaments, so that they are
easily shaken about by the wind,
shedding their pollen.
Left: 'Eggs-and-bacon', Lotus
corniculatus, Birdsfoot Trefoil is
adiiferent species to the Greater
Birdsfoot trefoil (shown above) and
has smaller leaves and flowers. Both
are found in this meadow, though the
lesser form became much more
dominant by August as the Greater
Birdsfoot trefoil was finishing flowering
(the lesser species flowers over a
longer period).
Trefoils have the typical pea-flower
morphology: with a large uppermost
'flag' or 'standard' petal, 2 lateral
'wings' and two petals fused together
to form the basal 'keel'.
corniculatus, Birdsfoot Trefoil is
adiiferent species to the Greater
Birdsfoot trefoil (shown above) and
has smaller leaves and flowers. Both
are found in this meadow, though the
lesser form became much more
dominant by August as the Greater
Birdsfoot trefoil was finishing flowering
(the lesser species flowers over a
longer period).
Trefoils have the typical pea-flower
morphology: with a large uppermost
'flag' or 'standard' petal, 2 lateral
'wings' and two petals fused together
to form the basal 'keel'.
Plantains
More Flowers
Vetches are another legume or pea-flower family member. They
have the characteristic pea-flower structure (like the trefoils) and
they may develop root nodules to fix nitrogen. The leaves are
compound and often the terminal leaflet is modified to form a tendril
(one tendril can be seen at the end of the leftmost leaf on the
close-up view on the left, disappearing out of the frame). The most
common species found in these meadows (and in one of the
meadows in particular) is the tufted vetch, Vicia cracca, with its
beautiful blue-purple flowers borne on one side of a floral spike.
These plants flower in June-August, but this year, in this meadow,
they have become more dominant, with the number flowering
increasing, in August as the trefoils go to seed.
have the characteristic pea-flower structure (like the trefoils) and
they may develop root nodules to fix nitrogen. The leaves are
compound and often the terminal leaflet is modified to form a tendril
(one tendril can be seen at the end of the leftmost leaf on the
close-up view on the left, disappearing out of the frame). The most
common species found in these meadows (and in one of the
meadows in particular) is the tufted vetch, Vicia cracca, with its
beautiful blue-purple flowers borne on one side of a floral spike.
These plants flower in June-August, but this year, in this meadow,
they have become more dominant, with the number flowering
increasing, in August as the trefoils go to seed.
Above: a Hay rattle gone to seed. By the end of July
most have finished flowering, the flowers are distinctive,
with small yellow beak-like flowers protruding between a
pair of clam-like green sepals, but the fruit gives the
plant its name - seeds can be heard rattling inside the
open papery fruits as they are shaken free by the wind
and by passing animals. This plant is a hemiparasite that
feeds off grasses.
most have finished flowering, the flowers are distinctive,
with small yellow beak-like flowers protruding between a
pair of clam-like green sepals, but the fruit gives the
plant its name - seeds can be heard rattling inside the
open papery fruits as they are shaken free by the wind
and by passing animals. This plant is a hemiparasite that
feeds off grasses.
Red Clover, Trifolium pratense, yet another
nitrogen-fixing legume of the peaflower family.
nitrogen-fixing legume of the peaflower family.
Above: a snapshot of the meadow - how many plant species can you identify? Can you explain some of their features of
biological significance?
biological significance?
I may have missed a chance to
photograph the flowers this year, but
the Arum fruit are easy to spot and
there are rather a lot of Arum near
here now in fruit.
photograph the flowers this year, but
the Arum fruit are easy to spot and
there are rather a lot of Arum near
here now in fruit.
The outer tubular florets of knapweed (Centaurea) are sterile and serve
only to attract pollinators. The inner florets have a special pollination
mechanism - when touched by an insect the stamen filaments rapidly
contract (in flowers with motile stamens this typically involves the
generation of electrical signals in the base of the stamen followed by
action potential propagation along the stamen). The anthers, which are
fused into a tube around the style are pulled back and the fixed style
pushing up amongst them pumps out the pollen onto the insect. To avoid
self-pollination, the stigma only becomes receptive when all the pollen is
shed, when the style extends out from the anther tube.
only to attract pollinators. The inner florets have a special pollination
mechanism - when touched by an insect the stamen filaments rapidly
contract (in flowers with motile stamens this typically involves the
generation of electrical signals in the base of the stamen followed by
action potential propagation along the stamen). The anthers, which are
fused into a tube around the style are pulled back and the fixed style
pushing up amongst them pumps out the pollen onto the insect. To avoid
self-pollination, the stigma only becomes receptive when all the pollen is
shed, when the style extends out from the anther tube.
Meadow Animals
The study of any meadow would not be complete without a mention of meadow animals. Clearly so many different animal species are
associated with meadows that i would not be able to mention them all, so i shall mention a few that I have seen in these meadows myself.
The six-spot Burnet moth, Zygaena filipendulae, with its vivid black and red colouration, the larvae feed on birdsfoot trefoil (Lotus
corniculatus). This moth is day-flying and found on the wing from June to August. (External link).
The Gatekeeper butterfly, Satyridae-Pyronia tithonus, whose larvae feed on grasses. (External link).
Soldier beetles, so-called because of their bright red and long straight bodies (like redcoat soldiers) which feed on insects, including
grasshopper eggs. Manny can be seen alighting on the grasses. (External link).
Anthills are prominent in parts of the meadows.
Rabbits are abundant here. I have seen many of them out of their burrows around midday. Their abundance is also evidenced by their
latrines (patches of short grass where they deposit their second droppings). Rabbits may crop the grass very short in places (and have
been known to destroy grass by cropping it too short). Rabbits were imported by the Normans in mediaeval times, for their fur and meat
(the mountain hare is a native to Britain, however). They live in communual subterranean burrows (warrens), consisting of a number of
chambers connected by tunnels. They are unable to fully digest cellulose on the first passage through their guts and will release the
first droppings whilst in their burrows, eating them (coprophagy) directly from the anus. These soft primary droppings are enclosed in
membranes and contain bacteria that carry on digesting the cellulose as the droppings are stored in the hind stomach. Secondary
droppings are deposited outside in designated areas (latrines) and are harder pellets. Rabbits used to be major crop pests, but
elimination by farmers and more so by myxomatosis, a disease of rabbits caused by the Myxoma virus which was introduced to control
rabbit populations. After initially decimating rabbit populations, they have been slowly recovering as they become more resistant and
the virus less virulent (a similar evolution toward equilibrium seen in dutch elm's disease). The disease still claims many young rabbits,
however. Currently rabbits are not serious pests in Britain. Apart from human beings, which do occasionally eat rabbits, their enemies
are cats, foxes and birds of prey, such as the red kites and hawks reported near here (the skreetching of a pair of raptors,
reportedly red kites, can be heard in the nearby woods). Cat and fox stools are similar in size and shape and I personally do not know
how to distinguish them, but I have found such near to the latrines, perhaps where a predator lay in ambush. Rabbits are not as
defenceless as they look, apart from being fast and agile and being able to dart into their burrows, they have powerful back legs with
sharp claws and their bite can be quite substantial.
Domestic cattle are periodically allowed to graze these meadows at certain times of the year. The cow-pat is an ecosystem all in itself
as well as adding valuable fibre (humus) and nitrogen to the soil.
The study of any meadow would not be complete without a mention of meadow animals. Clearly so many different animal species are
associated with meadows that i would not be able to mention them all, so i shall mention a few that I have seen in these meadows myself.
The six-spot Burnet moth, Zygaena filipendulae, with its vivid black and red colouration, the larvae feed on birdsfoot trefoil (Lotus
corniculatus). This moth is day-flying and found on the wing from June to August. (External link).
The Gatekeeper butterfly, Satyridae-Pyronia tithonus, whose larvae feed on grasses. (External link).
Soldier beetles, so-called because of their bright red and long straight bodies (like redcoat soldiers) which feed on insects, including
grasshopper eggs. Manny can be seen alighting on the grasses. (External link).
Anthills are prominent in parts of the meadows.
Rabbits are abundant here. I have seen many of them out of their burrows around midday. Their abundance is also evidenced by their
latrines (patches of short grass where they deposit their second droppings). Rabbits may crop the grass very short in places (and have
been known to destroy grass by cropping it too short). Rabbits were imported by the Normans in mediaeval times, for their fur and meat
(the mountain hare is a native to Britain, however). They live in communual subterranean burrows (warrens), consisting of a number of
chambers connected by tunnels. They are unable to fully digest cellulose on the first passage through their guts and will release the
first droppings whilst in their burrows, eating them (coprophagy) directly from the anus. These soft primary droppings are enclosed in
membranes and contain bacteria that carry on digesting the cellulose as the droppings are stored in the hind stomach. Secondary
droppings are deposited outside in designated areas (latrines) and are harder pellets. Rabbits used to be major crop pests, but
elimination by farmers and more so by myxomatosis, a disease of rabbits caused by the Myxoma virus which was introduced to control
rabbit populations. After initially decimating rabbit populations, they have been slowly recovering as they become more resistant and
the virus less virulent (a similar evolution toward equilibrium seen in dutch elm's disease). The disease still claims many young rabbits,
however. Currently rabbits are not serious pests in Britain. Apart from human beings, which do occasionally eat rabbits, their enemies
are cats, foxes and birds of prey, such as the red kites and hawks reported near here (the skreetching of a pair of raptors,
reportedly red kites, can be heard in the nearby woods). Cat and fox stools are similar in size and shape and I personally do not know
how to distinguish them, but I have found such near to the latrines, perhaps where a predator lay in ambush. Rabbits are not as
defenceless as they look, apart from being fast and agile and being able to dart into their burrows, they have powerful back legs with
sharp claws and their bite can be quite substantial.
Domestic cattle are periodically allowed to graze these meadows at certain times of the year. The cow-pat is an ecosystem all in itself
as well as adding valuable fibre (humus) and nitrogen to the soil.
Some grasses have
plantain-like flower spikes, like
the two shown on either side.
However, whereas plantains
grow from a cushion of
more-or-less broad leaves,
grasses have very narrow
leaves sheathing the stem.
The grasses shown here are
probably the Meadow Foxtail
(Alopecurus pratensis) which
grows on we meadows like
these. Timothy grass is also
present here, and this too has
a long cylindrical flower head.
The white or purple anthers
can be seen projecting from
the small flowers on long
stalks.
plantain-like flower spikes, like
the two shown on either side.
However, whereas plantains
grow from a cushion of
more-or-less broad leaves,
grasses have very narrow
leaves sheathing the stem.
The grasses shown here are
probably the Meadow Foxtail
(Alopecurus pratensis) which
grows on we meadows like
these. Timothy grass is also
present here, and this too has
a long cylindrical flower head.
The white or purple anthers
can be seen projecting from
the small flowers on long
stalks.
This study was based on certain meadows, and surrounding wooded areas, near a place called Canley Ford in the British
Isles. It is a small nature reserve, but even so it holds a wealth of species which exhibit biological phenomena that are largely
hidden from the casual observer. Far from being merely empty fields of grass (which some would probably say are 'itching to
be developed') this is a fascinating and rich habitat. If their are meadows or grass fields near to you, look more closely - you
may be very surprised by what you find!
Isles. It is a small nature reserve, but even so it holds a wealth of species which exhibit biological phenomena that are largely
hidden from the casual observer. Far from being merely empty fields of grass (which some would probably say are 'itching to
be developed') this is a fascinating and rich habitat. If their are meadows or grass fields near to you, look more closely - you
may be very surprised by what you find!
The Meadow Cranesbill (Geranium pratense) so-called
because of the long 'beak' of its fruit. I only noticed these
flowers at the end of July and they seem to have increased in
number at start of August in these meadows.
As August approached, other changes became apparent as
the hayrattles finished flowering and the number of birdsfoot
trefoil in flower diminished, the number of flowering
knapweeds seems to have increased considerably.
because of the long 'beak' of its fruit. I only noticed these
flowers at the end of July and they seem to have increased in
number at start of August in these meadows.
As August approached, other changes became apparent as
the hayrattles finished flowering and the number of birdsfoot
trefoil in flower diminished, the number of flowering
knapweeds seems to have increased considerably.
Parasitoids
Insect life is abundant and diverse in these meadows. This
caterpillar is motionless and probably dead. The culprit is
revealed by the small white pupae covering its body. These are
pupating parasitic wasps. The mother used her long 'sting' to
lay eggs inside the caterpillar and the grubs fed upon their
host's internal tissues, killing it and then emerging to form their
pupae, which will eventually hatch to release new adult wasps.
Animals, such as these wasps, which consume a single host to
complete their life-cycle are called parasitoids. In contrast,
parasites do not generally need to destroy their host in order to
infect another and predators consume a number of hosts.
Insect life is abundant and diverse in these meadows. This
caterpillar is motionless and probably dead. The culprit is
revealed by the small white pupae covering its body. These are
pupating parasitic wasps. The mother used her long 'sting' to
lay eggs inside the caterpillar and the grubs fed upon their
host's internal tissues, killing it and then emerging to form their
pupae, which will eventually hatch to release new adult wasps.
Animals, such as these wasps, which consume a single host to
complete their life-cycle are called parasitoids. In contrast,
parasites do not generally need to destroy their host in order to
infect another and predators consume a number of hosts.
Above: a Black Knapweed (Centaurea nigra) being pollinated
by a hoverfly (Episyrphus balteatus) - click to enlarge.
External links to hoverfies: microscopy-uk, wildlifeinsight.
by a hoverfly (Episyrphus balteatus) - click to enlarge.
External links to hoverfies: microscopy-uk, wildlifeinsight.