Nettles (Urticaceae)
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Urticaceae Family: Lamiaceae
Members of the Urticaceae are native to the Palaearctic region, and North Africa, but are now established in various regions worldwide, they may be recognized by the square section stems and stinging hairs, dead-nettles are sometimes superficially similar, they belong to the Lamiaceae and also have square-section stems but they lack stinging hairs and have very different flowers.
Stinging Nettle
(Urtica dioica, U. urens)
The common Stinging nettles are easily identified, they
are abundant across the UK, and is recorded up to
2,700 ft. It will grow in just about any habitat and on any
soil type, especially favouring higher phosphorus and
nitrogen soils, which are around human habitation and
can survive in moderate shade. The rhizomes have
difficulty penetrating compacted soil and it prefers open
textured soils of pH 5.0 to 8.0. In a clover/grass pasture,
it was noted that common nettle was more likely to be
associated with areas where clover was dominant than
where grasses made up the majority of the vegetation
cover. In unimproved pasture, common nettle increased
under annual cutting for hay. Stinging nettle is
particularly found as an understory plant in wetter
environments, but it is also found in meadows. Although
nutritious, it is not widely eaten by either wildlife or livestock, presumably because of the sting. It spreads by abundant seeds and also by rhizomes, and is often able to survive and re-establish quickly after fire.
There are two species of stinging nettle in the UK, the perennial common nettle, Urtica dioica L. and its varieties, while the smaller annual U. urens L. is more local and tends to grow in isolation.
Common nettle is variable in size, leaf shape and flower form, and several varieties
have been described. The leaves are technically described as lanceolate / oval, i.e.
they are spear shaped and have 'teeth' along their edge. The leaves are arranged in
pairs and set opposite to one another. Each pair is arranged at 90 degrees to the
previous pair. The nettle leaf is probably best known because its ability to sting. The
square section stems and on the surface of the nettle leaf are many hollow, hair-like
tube structures, known as trichomes, which are finely tipped with silicon, rather like
glass. The tip of the tube is easily broken, leaving a sharp point that will easily
penetrate human flesh. Each trichome and its swollen base is filled with a cocktail of
chemicals, which includes histamine, serotonin, formic acid and acetylcholine. They
inject this mixture of chemicals including histamines that produce an immediate stinging sensation and result in the characteristic rash of a nettle sting, known as contact urticaria, which varies between individuals but is usually painful, produces local swelling and lasts for about 15 minutes.
Rarely there may be individual plants or local populations that lack stinging hairs, most notably at Wicken Fen in Cambridgeshire, but these usually occur at low frequency and there is no evidence to suggest they are either spreading or that they represent a different species although some view it as a sub species called 'fen' or 'stingless nettle' (Urtica dioica subsp. galeopsifolia).
Common nettle requires long days to stimulate flowering and flowers from May to September, but is
inhibited by drought or shade. Flowering on individual plants is protracted and may last several
months. Plants do not flower in their first year. The specific name doica refers to the fact that the
common nettle has only male or female flowers on any one plant. The male and female plants tend
to grow together in large clumps, sometimes in clearly defined female and male sides to the patch,
they both produce small flowers in arching arrays at the base of the leaves, greenish / white with
yellow anthers. Individual flowers are small but they are produced in abundance and so attract
insects, some of which are more attracted to flowers of a particular sex. The anthers are bent down
whilst in the flower buds but when ripe, they spring upwards and release a cloud of smooth pollen to
be carried away on the wind. That is, nettles are wind pollinated or anemophilous. Flowers on male
plants are brilliant yellow from the pollen produced on the anthers while those on female plants have a finely pubescent white or silvery appearance. Rare hermaphrodite flowers are occasionally produced that contain parts of both sexes, and sometimes hermaphrodite plants occur where the upper and lower parts of the plants produce flowers of different sexes. Plants cut down in flower do not produce viable seed. Plants cut when the perianths are green but with the seeds at the milk stage, ripen seeds that germinate normally.
Nettle plants can produce large quantities of seeds, it has been estimated that a plant growing in the shade can produce between 500 to 5000 seeds, whereas one in the full sun may produce up to 20,000 seeds. Most seeds are short lived but some viable seeds remained after 5 years even in cultivated soil. Seeds have been recorded in large numbers in the soil beneath pastures even when the plant was poorly represented in the vegetation, and seed viability was not affected by dry storage in the first 2 years. The seed enclosed in its perianth can catch on clothing and animal fur to aid dispersal. Common nettle seed has been found as a contaminant in samples of grass seed. Common nettle seeds are ingested by worms and excreted in wormcasts. Seeds are also dispersed in the droppings of cattle deer and magpies. The seeds can float in water for one week.
Seeds are able to germinate immediately on a bare soil in full sunlight but germination is delayed in closed vegetation. Seedlings appear from March onwards mostly from bare soil. The concentration of phosphate in the soil can influence seedling distribution. A low concentration can restrict early growth. Nettle seedlings grow rapidly in the first few weeks to stay above the developing vegetation. Seeds sown in field soil and cultivated periodically emerge sporadically through the year with a peak in April.
The common nettle will colonize new habitats from seeds dispersed by the wind or by insects and other animals, but once they become established they produce vigorous rhizomes which soon give rise to dense stands of plants which tend to exclude other species. Common nettles thrive on disturbed ground, the natural habitat was probably open woodland on moist or peaty soils and the present day abundance of the species is largely due to human habitat modification, they grow vigorously on phosphate-rich soils and so thrive on farm land and pasture, they quickly invade allotments and gardens and are often associated with rabbit warrens or ground disturbed by moles and other small mammals. Nettles are also very resistant to physical damage and grazing as the rhizomes continue to grow and produce abundant growth during spring and early summer. Common nettle has tough yellow roots and creeping stems rooting at the nodes. The horizontal shoots develop a short distance below the soil surface. New rhizomes are formed in late summer or autumn from older rhizomes or from the stem bases of aerial shoots enabling the plant to spread rapidly. They continue to grow until the death of the aerial shoots and they then turn upwards to form new shoots. The shoot tips may die back if frosted. Under prolonged drought conditions, vegetative growth is restricted. The plant overwinters as rhizomes with short green shoots. Rhizomes broken up by cultivation readily re-root.
They are among the first plants to grow in the spring and quickly produce dense carpets of low tender foliage, although this may new growth may emerge in the autumn and persist through the winter in sheltered situations or mild seasons, they recover quickly from physical damage or fire and may be transported to new sites as fragments of rhizome in top soil but they cannot withstand regular mowing or ploughing etc.
Common nettle is an important alternative host of
carrot fly and removal of nettles from hedgerows
has been suggested as a means to suppress the
pest. However, a range of aphid species that are
fed on by beneficial predator insects also infests it.
Common nettle is the main food plant for the
caterpillars of several butterfly species, such as the
Red Admiral, Peacock, Comma and the Small
tortoiseshell. It is also eaten by the larvae of some
moths including angle shades, buff ermine, dot
moth, the flame, the gothic, grey chi, grey pug,
lesser broad-bordered yellow underwing, mouse
moth, setaceous Hebrew character, and small
angle shades. The roots are sometimes eaten by
the larva of the ghost moth (Hepialus humuli).
Puccinia urticata (pictured right) is a rust fungus
which develops on the stems and leaves of
Stinging Nettle or Small Annual Nettle. It often starts as small orange blisters or swellings. Close
examination may reveal the pinhead-like fruiting
bodies of the fungus. The spores may spread to
other nettles or to various sedges where the telial stage of the lifecycle continues without causing a gall to form.
Small Nettle Urtica urens
The two main types of nettle are the Common (Urtica dioica), and Small (U. urens). The common nettle, as described before, is the one most likely found around the hedgerows followed by the Small Nettle. The Small nettle also stings and some people find it more painful than the common nettle. It is intolerant of heavy shading and prefers moist soil. The presence of small nettle is considered to be an indication of the need for lime.
Small nettles do not have separate female and male plants unlike the dioecious U. dioica, instead both sexes of flowers grow on same plant and are called 'monoecious', with many female and few male, in ascending spikes.
The smaller U. urens is an annual that grows to only about 2 foot in height and also stings, some people find it more painful than the common nettle. Common throughout Britain, especially in the east, it is a summer annual found on cultivated ground and waste places, particularly on light soils. It occurs up to 1,650 ft, is typically a darker green, the leaves are more coarsely toothed than U. dioica and has a characteristic appearance that quickly becomes familiar, but it may be distinguished by the leaves being arranged in a distinct compact stepping way. and the leaf stalk being longer than the leaf it supports, at least in fully developed leaves, but with the lower leaves shortly stalked, not long stalked. It lacks the yellow rhizomes of the common nettle. Plants tend to be small and are easily overlooked.
It is not frost tender. It is in flower from June to September, and the seeds ripen from July to October. The plant is not self-fertile. The average seed number per plant is around 1,000 but a large plant can have up to 40,000 seeds. The seeds have a persistent perianth that may catch on clothing and fur to aid dispersal. Viable seeds have been found in cattle droppings. Small nettle can be found in fruit for 4 months of the year. The time from germination to fruiting is around 100 days. Seedlings emerge from March to October with peaks in April and July. Seeds produced early in the year may germinate at once those shed later germinate the following year. Buried seeds require light for germination but just a 5 second flash is sufficient. Seeds germinate well in partial shade but bright light inhibits germination. Seedlings are also sensitive to UV radiation. The seeds are killed by soil solarization.
Dead Nettles
(Lamiaceae sp)
Dead Nettles are plants sometimes confused with stinging nettles, they are actually in the mint family although they have no mint flavour.
Though superficially similar to species of Urtica in appearance, it is not related and does not sting, hence the name “dead-nettle”.
Found in Europe, including Britain, from Scandanavia south and east to Spain, the Himalayas, and Japan. Preferring fields, hedgerows, woodland edges and clearings, and moist waste ground.
White Dead Nettle
(Lamium album)
White Dead-nettle is a flowering plant belonging to the mint
family, the Lamiaceae. It is a common perennial, short to
medium, faintly aromatic and patch forming plant, of roadside
verges, waste grounds and grassy banks, it likes semi-shade
and can be found growing up to 2 feet tall, in light woodland
areas or on hedge banks, often grows on fertile and
nitrogenous places beside stinging nettle, anywhere the
ground has been disturbed. Its white flowers appear from
March right the way through to December.
Looking similar to a stinging nettle, white dead-nettle is a hairy
perennial with heart-shaped, deeply toothed leaves. Dense
whorls of white, 'hooded' flowers appear up the stem, among the leaves.
The leaves
are 3–8 cm long and 2–5 cm wide, triangular with a rounded base, softly hairy, and
with a serrated margin and a petiole up to 5 cm long, growing in pairs on opposite
sides of the stalk. Like many other members of the Lamiaceae, they appear
superficially similar to those of the Stinging nettle (Urtica dioica) but do not sting,
hence the common name “dead-nettle”.
The leaves and flowers appear from March right the way through to December, at
intervals along the length of the stem in an orderly fashion. The clusters have two
stalked leaves on opposing sides of the square stem and provide a contrasting
backdrop of green for the flowers. The flowers are white, but not pure white, faintly
suffused with green, they are produced in whorls (‘verticillasters’) on the upper part
Tough, square stems. Very fibrous and covered in small non-stinging hairs. Green to red/purple.
of the stem, with the individual flowers 1.5–2.5 cm long. Corolla irregular
(zygomorphic), fused, bilabiate, long-tubed, turning upwards. Upper lip convex; lower lip 3-lobed, central lobe obcordate, lateral lobes very small, tooth-like. Calyx almost regular (actinomorphic), 5-suoninen, 5-lobed, lobes roughly same length as calyx-tube. Stamens 4, of which 2 long and 2 short. Gynoecium composed of 2 fused carpels. Inflorescence composed of dense, spike-like, axillary whorls.
The flowers are visited by many types of insects, but mostly by bees. The lip of the flower provides a landing stage for bees and other insects that pollinate the flowers. Only insects with a long proboscis are able to reach the nectar way down at the bottom of the calyx-tube. They are directed to the right place by a whorl of hair, which simultaneously keeps small insects, which are useless to the plant from the point of view of pollination, at bay.
Red Dead Nettle
(Lamium purpureum)
The Red dead nettle an annual that is common and found
throughout the UK. This low to short, often purplish, hairy
and aromatic plant likes arable and waste land and can
also be found in gardens, hedgerows and on roadsides
or anywhere the ground has been disturbed or cultivated.
Like other members of the dead-nettle family, it doesn't
have stinging leaves.
Dense whorls of pinkish to bright red-purple 10-18mm,
zygomorphic 'hooded' flowers, with two lower lip petal
lobes and minute fang-like lobes between and a straight
corolla tube, appear up the square stem, clustered
amongst leaves towards the top of the plant. Red dead-
nettle has a long flowering season that can begin in
February and last until November.
The aromatic leaves are hairy, heart-shaped and
have toothed edges. Some leaves near the top of
the plant take on a purple tint. With unpleasant
fragrance. Leaves are 2-4cm, oval, blunt toothed,
and have fine hairs, stalked, with a 1–2 cm petiole,
with the lower bracts longer than wide. They are
green at the bottom and shade to purplish at the
top.
This plant can be mistaken for Henbit dead-nettle (Lamium amplexicaule) which
has similar leaves and flowers. They can be differentiated because red dead-nettle
leaves have short petioles (leaf stalks), compared to the unstalked leaves of Henbit
Dead-nettle.
It is a prominent source of pollen
for bees in March/April, when
bees need the pollen as protein
to build up their nest. Lots of
different species of long-tongued
insects visit the flowers of red
dead-nettle, including the red
mason bee and bumblebees. The
caterpillars of garden tiger, white
ermine and angle shades moths feed on the leaves.
Henbit Dead Nettle
(Lamium amplexicaule)
Henbit Dead Nettle, also known as common henbit, or greater
henbit, is a species of Lamium native to Europe, Asia and northern
Africa. The specific name refers to the amplexicaul leaves (leaves
grasping the stem).
It is a low-growing annual plant growing to 10–25 cm tall, with soft, finely hairy, short, erect, squarish stems.
The leaves are opposite pairs, often with long internodes,
rounded, 2–3 cm diameter, with a lobed margin. The lower leaves
are stalked and the upper ones stalkless, often fused, and
clasping the stems.
Flowering from May though to September, the flowers are pink to purple, 1.5–2 cm long. The flowers are relatively large and form a few-flowered terminal spike with axillary whorls. The calyx is regular with five lobes and closes up after flowering. The corolla is purplish-red, fused into a tube 15 to 20 mm long. The upper lip is convex, 3 to 5 mm long and the lower lip has three lobes, two small side ones and a larger central one 1.5 to 2.5 mm long. There are four stamens, two long and two short. The gynoecium has two fused carpels and the fruit is a four-chambered.
Flowering from May though to September, the flowers are pink to purple, 1.5–2 cm long. The flowers are relatively large and form a few-flowered terminal spike with axillary whorls. The calyx is regular with five lobes and closes up after flowering. The corolla is purplish-red, fused into a tube 15 to 20 mm long. The upper lip is convex, 3 to 5 mm long and the lower lip has three lobes, two small side ones and a larger central one 1.5 to 2.5 mm long. There are four stamens, two long and two short. The gynoecium has two fused carpels and the fruit is a four-chambered.
Corolla irregular (zygomorphic), purplish red, 15–
20 mm long, fused, bilabiate, long-tubed. Upper lip
convex, 3–5 mm long; lower lip 1.5–2.5 mm long,
central lobe obcordate, lateral lobes small. Calyx
almost regular (actinomorphic), 5-lobed, 5-veined,
lobes at most same length as calyx tube, closed
after flowering. Stamens 4, of which 2 short and
2 long. Gynoecium composed of 2 fused carpels.
Inflorescence terminal, spike-like, comprised of dense, axillary whorls. Often also with small, unopened (cleistogamous) flowers. They are
self-pollinating because the corollas do not open to pollinators. They are often produced especially at cool times of year when there are no pollinators around. Thus the plant saves its resources and ensures pollination.
This plant flowers very early in the spring even in northern areas, and for most of the winter and the early spring in warmer locations. At times of year when there are not many pollinating insects, the flowers self-pollinate.
It propagates freely by seed, where it becomes a key part of a meadow ecosystem, where common, it is an important nectar and pollen
plant for bees, especially honeybees, where it helps start the spring build up. Its seeds have an oily appendage (elaiosome) which attracts ants on food-finding trips, which then spread the seeds to new habitats.
It can be difficult to differentiate between different species of red-flowered dead-nettle. Henbit dead-nettle’s uppermost stem leaves are amplexicaul: their cordate base surrounds the stem like a collar. There is also an important identification marker in the calyx, whose lobes close up after flowering. This is unlike its relatives.
Yellow Archangel
(Lamium galeobdolon)
Yellow Archangel is locally common in parts of England and Wales, but it is less so in West
Wales or the far north of Britain. Looking a bit like a stinging nettle, like other dead nettles
yellow archangel belongs to the mint family, Lamiaceae, and it resembles these in its
general shape and form. Plants can form dense patches with erect stems rarely taller than
30cm, and are stoloniferous, they produce rooting stolons, with long runners. Yellow
archangel is a hairy perennial with heart-shaped or oval, toothed leaves, and whorls of
yellow flowers , that appear on the upper half of the stem, in the leaf axils in early summer.
Like other dead nettles, flowers are lipped and hooded.
The plant prefers damp places and partial shade and is to be found in damp woodlands
and hedgerows, perhaps commoner on heavy soils. It is also to be found on the edges
of woodlands and tends to spring up after coppicing. It is regarded as an ancient woodland
species - it can spread by seed and its creeping runners. Being a perennial, Yellow
Archangel takes a time to become established, but once it gets established it can crowd
out most other plants. Some colonies are thought to have survived in some places for
hundreds of years in undisturbed sites often growing among Bluebells Hyacinthoides
non-scripta on woodland edges or within light deciduous woodland, and its yellow flowers
appear just as the Bluebells fade and die back. Partially-shaded hedge banks, ditches and
corners of scrubland are other places where Yellow Archangel sometimes grows wild.
The stems are finely hairy, as also are the long stalked, nettle like, toothed leaves. The
leaves arise in pairs opposite to one another and have marked tooth edges and the leaf
comes to a point at its apex. The leaves are a deep green. The leaves (and flowers) if
crushed or bruised give off a characteristic, somewhat acrid smell.
When at the bud stage, the flowers are
like small, round, yellow bubbles and is in
flower between April and June. The flower
lips are bright yellow, as are the insides
which are decorated with reddish brown
markings, known as honey guide
markings, that are said to direct pollinating
insects towards the flower's store of
nectar at the back of the flower. As they
collect the nectar, pollen is deposited on
the stigma - leading to fertilisation.
Noticeably fringed with eyelash-like hairs, the upper lip is single-lobed and helmet
shaped, while the less hairy lower lip is divided into three lobes. Individual flowers are
17 to 21mm long and form typically three moderately-spaced tight whorls around the stem.
Variegated yellow archangel
Lamium galeobdolon subsp. argentatum
Naturalised plants of the variegated garden sub-species argentatum can sometimes be
found. These have silvery markings on the leaves. The garden variety is rampant invader
and can out-compete native flora, but is a useful garden nectar plant, particularly for
long-tongued bees.
Once this species gets into the wild, it rapidly spreads and carpets the floor to the exclusion
of other plants. The smallest stolon fragment with just one pair of leaves can grow into a
new colony, and stolons break readily if the plant is pulled up. It’s usually found in shady
habitats such as woodland edges, hedgerows, roadside banks and stream sides. It is
increasing rapidly in the wild and beginning to impact sites at which species of conservation
interest grow.
Critical Risk
This sub-species is listed on Schedule 9 of the Wildlife and Countryside Act in England and
Wales therefore, it is also an offence to plant or otherwise cause to grow this sub-species in
the wild.
Selfheal
(Prunella vulgaris)
Selfheal is a low-growing, perennial, with a creeping habit, with rooting stems, and is
a member of the labiate family - Lamiaceae, as are the mints and deadnettles. They
have the characteristic two lipped flowers, in flower from June onwards, which are
carried on 'square' stems. It is described as downy or soft to the touch. It likes the
short turf of grasslands, roadside verges or even lawns, and is often found in grassy
places and hedgerows. Selfheal often forms a mat and is tolerant of poor soils. This
rapid coloniser of wasteland will persist even in grassy paths, lawns and public parks
that are subject to frequent walking. Its name derives from its former use by herbalists
for cuts, sore throats and skin inflammations
The stem is roughly square in cross-section, with a height of 5-30cm, weak stems
cause the plant to grow sideways before reaching upwards. Small hairs may be seen
on the stem.
Its leaves are hairy, stalked, scarcely toothed, often purple tinged and oval to diamond
-shaped and are not particularly pointed, about 2.5 cm long and 1.5 cm broad, and
growing in opposite pairs down the stem. Each leaf has 3-7 veins that shoot off the
middle vein to the margin. The stalks of the leaves are generally short, but can be up
to 5 cm long. The lower leaves may have a more pronounced leaf stalk or petiole.
Selfheal flowers from June to October. The flowers may be arranged in a square
shape cluster (when viewed from above), on the top of its stems, and are generally
a bluish or violet colour, but can have a more pinkish hue. Each flower has four
stamens and the petals form two prominent lips. The upper lip is a helmet-like cowl,
while the lower lip is divided into three lobes, the central lobe longer than the two
side lobes. The sepals (calyx) are clearly visible, and pointed and distinguish the plant
from others in the mint family by their tight, sausage-shaped whorl. Its purple-tinged seed head
remains after flowering.
Self-heal propagates both by seed and vegetatively by creeping stems that root at the nodes.
Two subspecies of Prunella vulgaris have been identified: var. vulgaris and var. lanceolota.
Large Flowered Hemp nettle
(Galeopsis speciosa)
Galeopsis speciosa is a annual herbaceous plant in the family
Lamiaceae, growing to 1 m. It favours nutritious, preferably
nitrogenous habitats with mildly acid, neutral and mildly
alkaline soils, and is usually found growing in arable land,
waste ground, gardens, soil heaps, forest margins, roadsides.
It can grow in semi-shade (light woodland) or no shade. It
prefers moist soil. It is native to Northern and Central Europe
and Siberia.
The plant is poisonous and causes temporary paralysis of limbs, especially when the organism is heated by work.
The stem branching with swollen joints, 4-edged, often with purple base, joints and
edges, rough-haired mainly along edges, lacking glandular hairs. The Leaves are
opposite and stalked. With a blade that is ovate, sharp-tipped. The leaf is feather-
veined, smoothly haired and the margin has large, sharp teeth.
It is in flower from July to September and is hermaphrodite (has both male and female
organs). It is usually pollinated by Insects, but can also be self-fertile. The corolla is
irregular (zygomorphic), pale yellow, occasionally white or reddish, 20–35 mm long,
fused, bilabiate, long-tubed and hairy. The upper lip is convex; lower lip 3-lobed, with
the central lobe purple, base with 2 glands. Calyx campanulate (bell-shaped), 5-lobed,
the lobes are rigid and sharp-pointed. The 4 stamens, of which 2 are short and 2 are
long. Gynoecium is composed of 2 fused carpels. Inflorescence lower part with long
gaps, upper part denser, spike-like group formed of dense axillary whorls terminating
stems and branches. It can only be pollinated by long-tongued bumblebees and honeybees which can reach down to the bottom of the flower and drink the abundant nectar.
The plants can produce hundreds of seeds and like its relatives, large-flowered hemp-nettle is able to throw its seeds a short distance as the calyx dries and suddenly collapses, throwing the seeds out. The spiny calyx attaches to people’s clothes and animal fur. The spines also protect the plant from being eaten.
Hedge
Woundwort
(Stachys sylvatica)
A member of the mint family the Hedge Woundwort, also known as Wood Woundwort, Hedge Nettle and Red Archangel, is an erect perennial plant that can grow anywhere between 30cm and 1 metre high and forms patches in shady places. This common perennial wildflower can be found countrywide growing in shaded areas at the edge of woodlands and along hedgerows and roadside verges, Hedge woundwort is a plant with an unpleasant and astringent smell. This smell is particularly apparent when the plant is crushed. As its name suggests, this wildflower was used as a herbal remedy to staunch bleeding and heal tissue.
As with other members of the Stachys genus, the solid stems of Hedge
Woundwort have a square cross section, and they may be either
unbranched or very occasionally branched. The stems are more
noticeably hairy in the upper region of the plant, and there are nodes
widely spaced along the stem. From each node emerges a pair of
opposite, elongated heart shaped, stalked, hairy leaves. These are
toothed very similar to the leaves of Stinging Nettles. (When it is not in
flower, it is all too easy to mistake Hedge Woundwort for a nettle,
however, like other Dead Nettles, the leaves species do not sting.)
There is no rosette of basal leaves.
In Britain the main blooming period of Hedge Woundwort is July and
August. It is usually possible to find a few early flowers in June and
stragglers as late as the end of September or some years even into mid
October. The small, 13 to 18 mm long, dull dark purple red, hooded,
flowers with white markings towards the centre, are arranged in tight
whorls around the top of the plant stem, the whorls forming an interrupted spike. and are dark purple in colour with white markings towards the centre.
Hedge Woundwort is a prolific seed maker and once the seed is dispersed, can also spread vigorously by means of slender underground rhizomes.
This relative of Marsh Woundwort, Stachys sylvatica favours the edges of deciduous woodlands and hedgerows, but it can also be seen occasionally beside rivers and lakes, where Marsh Woundwort also occurs. Honeybees and bumblebees also like to visit the flowers of both Hedge Woundwort and Marsh Woundwort; this, when the two species are growing in close proximity, can as a result of cross pollination and so produce woundwort hybrids. Marsh Woundwort is similar in stature and form but has paler flowers and unstalked leaves; the leaves of Hedge Woundwort are stalked.
Yellow Rattle
(Rhinanthus minor)
One of our most important meadow wild flowers. An annual, herbaceous wildflower
in the genus Rhinanthus, in the family Orobanchaceae (the broomrapes). It has a
circumpolar distribution in Europe, Western Asia, and Northern North America.
Widespread, on nutrient-poor grasslands, including permanent pastures, hay
meadows and dunes. Also on roadsides and waste ground. Yellow-rattle is an
annual that thrives in grasslands, it is hemi-parasitical on grasses, notably on
Poaceae (grasses) and Fabaceae (legumes), and so, living a semi-parasitic life by
feeding off the nutrients in the roots of nearby vigorous grasses, weakens them,
thereby giving other, more delicate, traditional wild flowers a chance to push their
way through and compete, gradually establishing themselves. For this reason, it was
once seen as an indicator of poor grassland by farmers, or considered to be a pest,
as it reduces grass growth, but is now often used to turn improved grassland back
to meadow. Yellow rattle resembles the larger greater yellow rattle (Rhinanthus
angustifolius).
Yellow rattle underwent a marked decline in Britain throughout the 20th century,
thought to be a result of changes in farming practices.
An erect plant with upright stems growing to 10–50 cm tall without many leaves, can
be simple or branched, is four-angled and often streaked or spotted black.
The leaves are simple, sessile (they grow directly from the stem) measuring 20 to
30 mm × 5–8 mm and opposite, somewhat heart-shaped at the base, otherwise
ovate (oval-shaped) to lanceolate (shaped like a lance tip), serrated or dentate
(toothed) and scabrid (a little rough to the touch). With heavy, dark veins, which
sprout opposite each other all the way up the stem.
The plant’s leaves make a yellow dye
In flower from May to July. It used to be said that when the yellow rattle was in flower, the hay was ready for cutting. Yellow-rattle has yellow, 13 to 15 mm across, tube-like flowers protruding from an inflated, green calyx.
When the flowers of yellow-rattle fade, the brown calyxes (containing the sepals) behind them becomes a silvery sphere in which the tiny seeds ripen can be seen and heard - they give a distinctive 'rattle', hence the common name.
Yellow-rattle is the food plant for the larvae of two rare moths, including the grass rivulet.
Cattle love yellow rattle – when let into a field it is the first thing they will eat
meadow maker
Yellow rattle is often described as the ‘meadow maker’ due to its ability to create or restore wildflower meadows, where it maintains species diversity by suppressing dominant vigorous grasses within a meadow as this semi-parasitic wildflower soaks up and feeds off the nutrients that neighbouring grasses need. As a result of this, therefore allowing other wildflowers to flourish and the recycling of soil nutrients. .
The seed is sown thinly onto grassland from August to November—to germinate the following spring, the seeds need to remain in the soil throughout the winter months.
Once established, Yellow Rattle will allow for other wildflowers to grow and establish without the threat of grasses or weeds taking over.
Whilst Yellow Rattle evidently has its benefits, once established, Yellow Rattle will allow for other wildflowers to grow and establish without the threat of grasses or weeds taking over.
Yellow Rattle is an annual, so needs to be sown at a certain time to achieve the desired effect. The process for sowing Yellow Rattle should begin at the end of summer when you mow the area as short as you can, removing the clippings. Following this, you should heavily scarify the area to achieve at least 50% bare / exposed soil. When you sow your Yellow Rattle seeds, they need to make contact with the soil and become embedded. Typically, any wildflower seed requires consistently freezing temperatures to germinate in a process called stratification. not leaving the sowing of Yellow Rattle any later than November, so as not to delay a spring showing.
● Cut your grass as short as possible at the end of summer and scarify your existing meadow / grassland with an aim to achieve 50% bare / exposed soil
● Sow your Yellow Rattle before winter sets in (do not leave sowing any later than November) – it will germinate and bloom in early spring and begin to weaken the existing grasses.
● Scatter the seed at a rate of 5g per m2 and rake the seed so that it is in amongst the soil
● Water the just-sown wildflower seed well
● If sowing in drought conditions, water as required to keep the area moist in the first 6 weeks after sowing
Although Yellow Rattle is an annual, you shouldn’t need to add more in subsequent years as it will produce more seeds and drop them into the soil.
Thistles (Asteraceae)
Thistles belong to what is, after grasses, the largest family of flowering plants in the Britain, the daisy family (Asteraceae). The flower heads are made up of a number of individual flowers or florets giving rise to this family being called “composites”. Thistles are characterised by leaves with sharp prickles on the margins and on the stem. These prickles are an adaptation that protects the plant from being eaten by herbivores.
The leaves and nectar of thistles are very good sources of food for many insects, such as butterflies and especially the caterpillars of the Painted Lady, and some birds, such as Goldfinch, which eat the seeds.
Thistle plants provide a great deal of nectar for pollinators. According to a UK plants survey conducted by the AgriLand project which is supported by the UK Insect Pollinators Initiative The Creeping thistle came in second place, with the Spear thistle in third and beaten only by Ragwort for the "Mean nectar sugar mass per 24h per floral unit for species in native weeds in either the annual seed mix, or the perennial seed mix, for nectar production (nectar per unit cover per year) with a production per floral unit of (2300 ± 400 μg).
There are two groups of thistles: Carduus and Cirsium. These can be differentiated by the pappus. The pappus is the part that surrounds the base of the corolla tube in the individual floret.
Carduus – those with simple pappus hairs and a bristly receptacle. Where the hairs are unbranched.
Cirsium (or Plume-thistles) – those with a pappus of feathery hairs and are branched and feathery.
Spear thistle = spiney stems and bracts, green under leaf, purple flowers
Creeping thistle = spineless stems and bracts, white or grey under leaf, lilac flowers
Marsh thistle = spiney stems and weakly spined bracts, green under leaf, purple flowers
Spear Thistle (Cirsium vulgare)
A very common biennial throughout Britain, that
rises to over a metre in height. Thistle flowers
bloom singly or in clusters from midsummer through
to early autumn in a wide array of habitats, including
overgrazed pastures and rough grassland, sea-cliffs,
dunes, and well-drained, disturbed habitats where
soil fertility is high, including arable fields, spoil
heaps, waste ground and cleared areas in
woodland.
A native of Eurasia, its range extends from the
Atlantic coast of Europe to the Pacific coast of
China, and is closely linked to the distribution of
cultivated land. Wherever Europeans have migrated,
the spear thistle has been introduced in their wake,
for example, to Colonial North America and
nineteenth-century temperate South America and
Australasia.
Spear thistles are usually biennial, producing a rosette of leaves with a deep taproot during their first year of growth following seed germination. Flowering happens in the second year; the plant then dies. The plant develops two types of leaves, the basal leaves grow from a rosette. The upper surface of leaves are dull green and prickly-hairy on the upper surface. These are lanceolate, spear shaped, pinnately deeply lobed and the margins are covered in sharp spines.
From the centre of the rosette an elongated flowering stalk emerges, which can be up to 1.5 metres tall. The leaves from this are spear shaped and much smaller.
Thistle flowers bloom singly or in clusters from midsummer through to early autumn. The flowers form a lilac-purple to mauve inflorescence that can be up to 5cm in diameter in a panicle or flat topped cluster. Flower bracts straight, with a yellow spine. One of the key ID features of thistles are the overlapping bracts (involucre) found directly below the flowers. Up to 200 fruits may form in each flower head. There are reports of individual plants producing over 50,000 fruits.
Spear thistle fruits, as with all Cirsium, have individually feathery, silky white hairs attached to the seed - the thistledown to aid wind dispersal. However, the fruits are not dispersed by wind over long distances; the pappus is readily detached. In late summer pappi are often seen floating in the air. Fruits are effectively dispersed by animals such as birds and as contaminants of animal fodder. Despite the numbers of fruits a single plant produces, herbivory of flowering stems and predation by animals of the oil-rich seed means few spear thistle seedlings survive to maturity. The fruits survive about five years in the seed bank but most germinate soon after release from the parent plant.
Creeping Thistle
(Cirsium arvense)
The Creeping thistle is our most common species of thistle, and possibly is the
most important perennial thistle. It is native and found throughout the British Isles and provides a food source for a range of insects and birds. Found in disturbed and cultivated fields, rough grassland, waste places, hedgerows and verges and is recorded up to 2,300 ft. It is an aggressive weed that occurs on most soils but it grows more extensively on deep, well-aerated soils. Its lateral creeping roots, which are brittle and readily re-shoot if broken, enable it to quickly spread across an area, forming large colonies. As with other thistles, it can become a nuisance on agricultural land and this species is often considered to be a weed.
A medium to tall plant, stem usually branched, but not winged, or with very short
wings nor spiny. Leaves are green underneath, lanceolate to oblong, pinnately lobed or unlobed, spiny, the upper leaves unstalked.
There are few marginal spines on creeping thistle. The large second leaf of spear thistle is densely hairy.
It produces a tap root on germination followed by lateral roots that grow
horizontally. These lateral roots are brittle and produce buds at intervals that
develop shoots. Spreading roots mean that the thistles form large clumps of spiny leaves and flowering stems ranging from 30cm-1m in height which can expand at the rate of 6 m per year. It easily regenerates from broken pieces. Individual plants, can form large clumps. They are dioecious (either male or female) being virtually self-sterile. However, male and female plants growing adjacent to each other will cross-pollinate and a seed crop will be produced
Lighter pink that most other thistles, the Creeping thistle has flower heads with
lilac-pink florets on top of a small cylinder of spiny bracts, 15 to 25 mm, fragrant,
solitary or from 2 to 5 together, are borne July to September.
Creeping thistle is less likely to set fertile seed than other thistles. The plant dies back in winter while seeds are still retained in the seed head. The separate sexes need to be within a few hundred metres for seeds to be fertile, although some plants may be self-fertile. Only about 3% of the seed is viable.
As with all Cirsium, the pappus-hairs (the silky white hairs attached to the seed - the thistledown) are individually feathery or branched.
Creeping thisle (Cirsium arvense) is covered by the Weeds Act 1959 (which specifies five injurious weeds including creeping thistle).
Marsh Thistle (Cirsium palustre)
Britain’s tallest thistle, up to 2 metres, although more typically 1 m
tall is common throughout Britain. This biennial thistle, does, as its
name suggests, grow in boggy ground, wet habitats, woodland
clearings, wet ditches and marshes.
Similar looking to Creeping Thistle but Marsh Thistle has got prickly
stems spiny-winged to the top, sometimes branched above. The
stems of Creeping Thistle are smooth. The strong stems have few
branches and are covered in small spines. In the subsequent years
the plant grows a tall, straight stem, the tip of which branches
repeatedly,
The leaves linear lanceolate, pinnately lobed and very spiny, mostly
unstalked, hairy above.
The leaves are alternately arranged along the stems, linear
lanceolate, pinnately lobed and very spiny, mostly unstalked,
hairy above. The pinnate leaves are very prickly and deeply
lobed. In its first year the plant grows as a dense rosette, at first
with narrow, entire leaves with spiny, dark purple edges; later,
larger leaves are lobed. The upper surface of leaves not bristly
(often shiny).
A candelabra of dark purple flowers are produced from June to
September and are usually purple, 10 to 12 mm in clusters of 2 to 8.
Flower bracts purple tinged, erect, weakly spiny. The flowers are
occasionally white, in which case the purple edges to the leaves
are absent. These flowers are so rich in pollen that it is known to
be visited by at least 80 species of bee, butterfly and fly.
As with all Cirsium, the pappus-hairs (the silky white hairs attached
to the seed - the thistledown) are individually feathery or branched.
Rough Sow Thistle (Sonchus asper)
Very common throughout Britain except in some parts of the Scottish Highlands in the tribe Cichorieae within the family Asteraceae. Sonchus asper is native to Europe, North Africa, and western Asia. It has also become naturalized on other continents and is regarded as a noxious, invasive weed in many places. Its edible leaves make a palatable and nutritious leaf vegetable. Tasting just like lettuce and can be found throughout the year unless there is a really harsh Winter. There are eight species of sow thistle growing in the UK. It is generally less abundant than the smooth sow-thistle, S. oleraceus.
It is found in cultivated soil, pastures, roadsides, edges of yards, vacant lots, construction sites, waste areas and in grasslands. Since it is palatable in the young stages it does not normally survive in grazed pasture. It is recorded up to 1,500ft in the UK. Rough sow-thistle grows on most soils but prefers well drained slightly acid to alkaline soils, and has some tolerance of saline conditions. They grow mainly through the winter and usually die after flowering.
Rough or Prickly Sow Thistle is an erect, short to tall plant, branched, especially towards the top, annual or biennial herb about 20-150 cm tall with hollow stems, circular in cross section, which when cut, exudes a milky latex sap. The stems are leafy, shallow fluting, with a waxy bloom, often reddening, and have dark longitudinal striations, hairless or carry a few scattered purplish glandular hairs towards the top on the upper stem.
The two Cotyledons arise singly, the first being oval, with a rounded tip, 12 to 18 mm long overall with a very short merging petiole approximately 5 mm long. The base is tapered and hairless, or the upper surface may carry a few white multi-cellular hairs, and the margin is slightly toothed and spined. The seedling has a very short hypocotyl and no epicotyl. Later leaves are more lobed and usually hairless.
Initially growing in a basal rosette and toothed until the flower stem appears. The basal leaves are up to 30 cm long and 2-7 cm wide , with variously lobed, lanceolate (lance-shaped) or oblanceolate leaves, bright green to bluish-green, but often with a whitish bloom and form a rosette that is somewhat leathery and toothed with the teeth sometimes prickly. The end lobe is not wider than the upper side lobes.
The upper stem leaves are alternate with no petiole, hairless and the upper surface is shiny green and prickly, somewhat smaller and stem clasping with rounded, ear-shaped auricles, the leaves become less toothed the higher up the stem they are. The upper leaves carry a reduced number of lobes or no lobes at all, and are bent back.
Leaves can be very similar to S oleraceus but usually more sharply toothed. A number of ecotypes and varieties of Rough sow-thistle are described but environmental conditions also influence the appearance of the plant.
It flowers for much of the year but mainly from June to October. The flower heads are golden yellow, and like small Dandelion flowers but are branched and clustered, many can grow from one stem, unlike Dandelions, each about 2 cm in diameter, with all the tubular florets having a radiating petal-like blade, shorter than the tubes. Several head in a corymb at the ends of stems on stalks(peduncles) usually with dark glandular hairs, bracts without glandular hairs. The flowers are self-compatible.
The tiny fruits are brown, short and flattened, ovate-oblong to elliptic in outline, narrowed towards both ends, compressed, obtuse, ribbed lengthwise, glabrous, not beaked, margin narrowly winged, faces with 3-5 prominent lengthwise ribs on each face, which are never raised to form small wings, 2.5-3 mm long by 1.5 mm wide including the 2 wings which are usually hairy. Topped by a tuft of pappus of many, very fine, silky bristles intermixed with fine down like barbed hairs.
Mature seeds (achenes) are formed 1 week after flowering. The average number of seeds per flower head is 198, and a plant often has over 100 flower heads. Seed numbers per plant generally range from 21,500 to 25,000 but a large plant may have 60,000. In a competitive cereal crop a plant may have just 500 seeds. Moisture stress also reduces the number of seeds formed. Rough sow-thistle can be found in fruit for over 3 months of the year. The half-life of seeds in cultivated soil is just 1 year while in dry storage it is 2-3 years.
Seed is mainly spread by wind and seeds have been collected by aircraft at 2,000 ft. Under damp conditions the pappus of hairs collapses and dispersal is prevented.
The seeds germination is from autumn to spring. Light and stratification at low temperatures stimulate germination. Seeds on the soil surface germinate better than those buried at 30 mm deep. Seedling emergence occurs from March to November, with peaks in March-April and August to November, but odd seedlings can germinate at any time. Spring emerging seedlings reach the rosette stage after 6 weeks. This is followed by flower bud formation and stem elongation.
The seeds are eaten by birds and viable seeds may be found in their droppings. Viable seeds have also been found in cow manure. Rough sow-thistle seeds ingested by earthworms have been found intact in the worm casts. The seeds have been recovered from irrigation water. Rough sow-thistle seeds have been found as a contaminant in clover, grass and cereal seeds, particularly in home saved cereal seed.
Rough sow-thistle has been used as a potherb since ancient times. It is host to various aphids and acts as a reservoir to several important plant viruses including beet western yellows.
Smooth Sow Thistle
(Sonchus oleraceus)
Widespread and very common throughout Britain except for parts of the Scottish Highlands, found in most temperate regions, but is native of Europe and Asia. Smooth or Common Sow Thistle is a native annual or overwintering weed common on arable land on most soils throughout the UK in garden borders, plant pots, and waste ground, and is a pioneer species that colonises disturbed ground but it prefers sunshine and moist, nutrient rich soils up to 1,250ft. It has a broad tolerance of climatic variation and is also found on wasteland, roadsides and in gardens. Increasingly found in arable rotations particularly in winter crops. Autumn germinating plants can overwinter as rosettes and flower in May, spring germinating plants flower in June
There are a few different types of Sow Thistle species growing in the UK, but the Smooth sow-thistle (Sonchus oleraceus) is the most common followed by the Rough sow-thistle (Sonchus asper). There is also a perennial species, Corn sow-thistle (Sonchus arvensis). The genus Sonchus belongs to the daisy family, the Asteraceae. Sonchus asper and S. oleraceus are very similar in appearance, Infact the plants are so much alike that they were originally classed as the same species. Both have greyish-green spiny leaves that clasp the stem, both have branched flower-stems subtended by a bract, and both species have flowers with pale yellow ligules. They often grow together in the same habitats, developing and flowering at the same time, early in the season from April onwards. The third native species with very nearly the same general distribution in the British Isles is the perennial corn sow-thistle, Sonchus arvensis, is a much larger plant than the two annual species, with large, showy, deep yellow dandelion-like flowers that appear in late summer. Unlike the
annual species, it may spread by means of rhizomes to produce large patches, whereas the annual species always occur as individual plants.
Short to tall upright, greyish plant, 30–120 cm tall, sometimes tinged with red or purple. Smooth sow-thistle exhibits considerable variation in leaf form and flower colour. A number of ecotypes and varieties are described. Light levels also affect the appearance of the plant. In shady hedgerows the plants are green, in open areas they have a reddish hue.
The cotyledons are oval with very short stalks. The first leaf ends in prickles and is oval but cut almost square across to the stalk. It is edged with teeth pointing towards the centre of the plant, a single taproot is present below.
Initially growing in a basal rosette of shiny, greyish-green leaves that have deep, smooth lobes and are toothed, with pointed basal lobes. The alternate, basal leaves are stalked, with the stalks being channelled, narrowly winged and sparsely toothed, top dull bluish green, underside bluish grey. The edges of the leaves are covered with very small fragile soft spines. When the leaves are damaged, they exude a white sap or “latex” rather Dandelion like. Winter rosettes can withstand a moderate frost.
The plant throws up an upright flower stalk between June and August which is thick, smooth, hollow and branched, with the basal lobes surrounding stem. The upper leaves on the flower stalk have an elongated teardrop shape and wrap around the stem with pointed basal lobes. The leaves become less toothed the higher up the stem they are.
Sonchus oleraceus has leaves that are weakly and softly spiny, and usually deeply lobed, while those of the rough sow-thistle Sonchus asper are similar but its leaves are generally more aggressively spiny, less lobed, or unlobed, and the upper surface is shiny green. In both species the leaves clasp the stem by their ‘auricles’. The most striking and consistent difference between the two species is that the auricles of S. oleraceus are pointed, while those of S. asper are rounded. Smooth Sow-thistle and Common Sow-thistle often hybridise, resulting in plants with slightly prickly leaves.
Smooth Sow-thistle flowers first appear in April to May, but you may see this wildflower blooming as late as November or until the first frosts. The compound pale yellow flowerheads have yellow Dandelion-like flowers 2 to 2.5cm across, when fully open, surrounded by involucral bracts, that are borne in loose clusters. The stamens number 5 with the Gynoecium composed of 2 fused carpels.The outer ray florets are purplish underneath. Involucral bracts (max. 35) overlapping in 3 rows, dark green. The buds are cylindrical but the base of the flower is flask shaped, becoming more pronounced as the flowerhead dies. The flowers are hermaphroditic and self-fertile, and common pollinators include bees and flies.
S. oleraceus has flower stalks that are usually hairless, although the phyllaries have a few coarse hairs, but the phyllaries of S. asper, the flower stalks and sometimes the internodes below, are covered in dark reddish brown sticky glandular hairs. The latter also has larger capitula so it looks more impressive, although both plants’ flowers are a rather pale yellow. If there is still some confusion the number of involucral bracts can be counted. Like S. asper, the inflorescences and some lower internodes of S. arvensis are covered in glandular hairs, but in this species they are golden yellow, not dark red-brown.
Mature seeds are formed 1 week after flowering. Plant stems cut in bud do not ripen viable seed but the seed from plants cut in flower may be perfectly viable. The Smooth sow thistle only reproduces by seed and is distributed by wind. The average seed number per flower head is 140 and the number of flower heads per plant is around 44. The potential seed number per plant varies considerably with environmental conditions and estimates range from 5,000 to 40,000. Smooth sow-thistle can be found in fruit for 5 months of the year.
Achenes are flat, ridged with protuberances, brown, 2.5–4 mm long, transversely rugose, crowned with approx. 8 mm long unbranched hairs. The achenes of S. oleraceus are ridged with protuberances and are wrinkled between their ribs, whereas those of S. asper have glossy ridges and are smooth. The seed has a pappus of hair and is wind dispersed in dry conditions. Tests suggest maximum seed dispersal distances of 4.4 and 6.6 metres at wind speeds of 10.9 and 16.4 km/hour respectively but this would be affected by release height. In wet conditions the pappus collapses and dispersal is limited. Seed recovered from excavations and dated at 150 years old has been reported to germinate. However, the half-life of seed in cultivated soil may be just 1 year. Dry-stored seed remains viable for around 10 years. Smooth sow-thistle seed is susceptible to solarization. Smooth sow-thistle seeds have occurred as a contaminant in clover, grass and cereal seeds. The seeds form a part of the diet of several birds and seedlings have been found to emerge from their droppings. The seeds have been recovered from irrigation water and can float in water for several days.
Plants which germinate in autumn overwinter as rosettes, producing flowers in May/june; plants germinating in spring flower in June. The latter can set seed in 10 weeks. Under some conditions seeds require light for germination and this may restrict emergence in taller vegetation. The base temperature for germination ranges from 5.3 to 6.8°C. Seed germinates best on the soil surface or in the upper 20 mm layer.
Smooth sow-thistle does not survive beyond the seedling stage if it is shaded to any great extent. It cannot withstand repeated trampling and may be controlled by sheep grazing or mowing. It is grazed upon by rabbits and hares, deer and cattle.The flowers provide a source of nectar for pollinators during the summer months. The plant is attacked by a range of insects, fungi and bacteria and is host to several aphid species and nematodes. It acts as a reservoir for some important plant viruses such as beet western yellows.
Corn Sow Thistle (Sonchus arvensis)
Sonchus arvensis is native to Eurasia, where it is widespread across most of the continent. It has also become naturalized in many other regions. Although it occurs in all parts of the British Isles it is ‘locally frequent’, meaning that you might travel far before coming upon it, and then you may see many individuals. Its accepted English names include Perennial Sow-thistle and Corn Sow-thistle. Sow-thistles belong to the genus Sonchus. The two most common in our British Isles are S. oleraceus and S. asper. Nowadays we recognise just four Sonchus species in Britain, all named and described by Linnaeus (1707 – 1778). Both Rough Sow-thistle and Smooth Sow-thistle are similar, but Perennial Sow-thistle has larger, more showy and deeper yellow flowers. Smooth Sow-thistle has pointed leaf auricles and Rough Sow-thistle has prickly leaves. The fourth is S. palustris, the Marsh Sow-thistle but that one is only found in a few parts of SE England.
Sonchus arvensis differs from the other two species in being perennial and having much larger and brighter flowers and the fact that it reproduces vegetatively by means of tough rhizomes, and so it can be found forming clumps along roadsides in arable land and waste ground , waysides on banks, dunes and shingle by the sea, ditches and river-banks. It is recorded up to 1,500 ft in Britain and is considered to be of universal distribution on different soils. However, it prefers slightly alkaline to neutral soils and does not thrive in acid or highly alkaline soils. It grows better at higher levels of soil moisture. An arable and a coastal ecotype have been distinguished. The arable form does not survive on the dry, nutrient poor dunes while the coastal ecotype cannot tolerate periodic soil disturbance. The ecotypes also differ in germination requirements.
A medium to tall plant with a root system which consists of long, spreading rhizomes. The stems are erect, up to 1.5 metres tall, furrowed and bristly above. The plant may branch a little in the upper part, the stems are dull green, round and usually smooth, and often with hard or woody hollow bases.
The stems and leaves do not survive the winter, the foliage and fine roots die in Autumn and the plants overwinter as buds on the thickened roots and the underground stems of aerial shoots. The roots are found mainly in the top 15cm of soil and appear to live for at least 2 years. Radial extension of the roots is 2-3m per year. At a fairly early stage (5-7 leaves) some roots become ‘regenerative’, capable of sprouting leafy shoots. Thickened roots that have reached 1-1.5mm in diameter are able to regenerate when broken into fragments. Root segments less than 25mm long with well-developed buds can produce new plants. In the autumn, the roots develop a strong innate dormancy that is not broken by tillage. The vegetative spread is due to the development of stems that arise from buds on the swollen roots.
Shoot development from anywhere along the roots begins again the following spring. stems begin to elongate in mid-June with leaves 10–35cm long and 4–14cm wide with leaves and stems that are softly toothed. The lower leaves having tooth-shaped lobes and are alternate, 4x longer than wide, mostly pinnately divided with 2 to 5 lobes with tooth-shaped, pointed tips to the lobes. These are concentrated in the lower part of the stem. They have heart-shaped bases which have a pair of small rounded basal lobes (auricles) which clasp the stem, but are not united around the stem. All edges with small prickles. The leaf surfaces are green, free from hair, free from prickles along the underside mid-vein. Prickles only on the margins. Leaves also have milky juice. The upper leaves will be much shorter and less divided or not divided at all clasping the stem with rounded basal lobes rather like Smooth Sow-thistle. Viewed from below the leaves are greyish with round auricles rather like the Rough Sow-thistle, but the auricles are less obvious.
Flowering takes place from late July until early October. The flower buds (sepals) and upper parts of the stems are covered in distinctive, sticky, yellow hairs. It produces conspicuous golden yellow, showy and raggedy flower heads about 3–5cm wide, in loose clusters, at the top of the stems, not all open at one time, which are more or less self-sterile and are visited and pollinated by various types of insects, especially hoverflies of the genus Eristalis. The cluster is on a long stalk but each flower is on a short stalk, and the base of the cluster and at divisions of the cluster there may be small bracts. The flower heads are composed of numerous fertile ray florets with whitish corolla tubes with yellow rays, the rays, toothed at the tip, and as long as the tubes. Disc florets are lacking. The stamens (5) and anthers are pale yellow and tightly surround the pistil and style, which is exerted from the corolla during flowering. The flower head base (the involucre) has many green bracts (phyllaries) in 2 or 3 series, the outer series shorter, the inner series longer with pointed slightly recurved tips. All have a darker green mid-vein. There are two varieties, one with glandular hair on the phyllaries, and one without. The same condition applies to the flower stalks.
As well as spreading by rhizomes, Corn Sow Thistle, also produces abundant wind-dispersed seeds. Fertile flowers mature to a dry reddish-brown cypselae (seed resembling an achene), which bear the seed within, 2.5 to 3.5mm long, oblong to ellipsoid, without a beak, hairless, and they are transversely ribbed, with 4 to 5 ribs on each side and with a tuft of fine white hair for wind dispersion which enables the seeds to be transported long distances. Wind borne dispersal distances of 6-10 m have been recorded in light winds. Hooked cells at the tips of the pappus hairs enable the seeds to be carried on clothes and animal fur as a further aid to dispersal. An average of 46 seeds are produced per flower head. Seed number per plant is around 13,000 but a single flower stem with many heads may have over 9,000 seeds. Seeds produced by self-pollination are rarely viable. A few seeds become viable just 4 days after flowering. Full seed maturity is achieved after 10 days. Seeds are able to develop if the stems are cut down and left to dry 9 days after flowering. A few seeds may mature on stems cut down just 4 days after flowering. Viable seeds have been recovered from irrigation water but seeds of perennial sow-thistle do not survive long when submerged. Seeds have been found as a contaminant in home-saved cereal seed. Seeds ingested by earthworms have been recovered intact and viable in worm cast soil.
Normally the seeds germinate in the spring, triggered by fluctuating temperatures in the range 5-25 degrees Centigrade. Seed germination is comparatively rapid when day temperatures are high and night temperatures low. There is no absolute requirement for light but it does increase germination levels. In field studies, the main period of seedling emergence was March to May with a peak in April. However, when seed was sown soon after shedding in August around 80% had germinated within 26 days. The seeds appear to exhibit only a short period of dormancy and readily germinate when conditions are favourable. Most seeds germinate at 5 to 30 mm deep in soil. In favourable conditions a seedling may flower in its first year. Seeds may remain dormant in soil for at least 6 years. In cultivated soil seeds remain viable for up to 5 years.
Perennial sow-thistle is a host of several important crop pests and diseases. The plant is eaten by foraging animals including rabbits. Seeds of sow-thistle are often predated in the flower-head by beetle larvae. The plant is palatable to both cattle and sheep
Common Knapweed (Centaurea nigra)
An upright, hairy perennial with stiff erect ribbed stems, Common Knapweed grows up to a metre in height and its upper part branches freely. Somewhat thistle-like, knapweeds are readily distinguished from thistles by the absence of spines and prickles, and can be identified by its slightly spherical black/brown flower head, growing alone. Centaurea nigra is a species of flowering plant in the family Asteraceae that is native to Europe.
Common knapweed is a tall, native, grassland perennial of low to moderately fertile soils but is absent from very damp or acid sites. Habitats include meadows, pastures, road verges, field borders, waste ground, scrub land and woodland edges. It can persist for many years in both grazed pasture and neglected tussocky grassland. The flowers provide a great deal of nectar for pollinators and are pollinated by a wide range of insects including bees, flies, butterflies and beetles and the resulting seed heads attract goldfinches and other seed feeding birds. It was rated in the top five for most nectar production (nectar per unit cover per year) in a UK plants survey. It also placed second as a producer of nectar sugar per floral unit, among the meadow perennials, in another study in Britain.
Found throughout Britain, common Knapweed is a wild flower of meadows and other grassland habitats and grows wherever grass is not closely cropped. It can often be seen hedges and also on road verges where wildlife is allowed to thrive. It is often abundant beside lakes and streams, especially where grazing animals have been fenced off from the margins. It prefers a well-drained, low to moderately fertile soil in a sunny position and is tolerant of dry, alkaline soils, but is absent from very damp or acid sites. The distribution of C. nigra is stable. Forms on light soils in England and Wales are sometimes recognised as subsp. nemoralis. Elsewhere, subsp. nigra predominates. Intermediates occur where both subspecies grow, and also in the absence of subsp. nemoralis.
Greater knapweed - a close relation - is similar but its flowers are more garish and opulent and its leaves are fully lobed.
Common Knapweed leaves are up to 25cm long, dull green and finely hairy, but in other respects they vary greatly. Its leaves are linear to lance-like in shape with the upper leaves usually narrow and simple (without lobes) and untoothed, while the lower leaves are sometimes pinnately lobed and have coarse teeth. The lower leaves are stalked, whilst the upper ones are stalkless.
The thistle-like flower heads, which are in bloom from June to September, are slightly spherical black/brown flower head, growing alone, topped with an inflorescence of many purple, pink or (more rarely) white flowers, to 4cm across, which are hermaphrodite (having both male and female reproductive organs), and exist in two forms; rayed and un-rayed. The flower-head is hard and solid, a mass of dark-brown-fringed green bracts overlapping over each like roof tiles, triangular in shape. The fruit is a tan, hairy achene 2 or 3 millimetres long, sometimes with a tiny, dark pappus. However, in order to regenerate, it needs an opportunity to set seed and for that seed to become established into open ground.
Greater knapweed, which is always rayed, can look a little like the rayed form of Common knapweed but can be told apart by the following features. In Common knapweed the bracts that make up the ‘hard head’ are pale brown with black/brown bristly edges. However, the degree of overlap obscures most of the pale brown. In Greater knapweed these bracts are grey-green with black/brown bristly edges, but because there is less overlapping, much of the bract is still visible. In Common knapweed the leaves of the upper stem are lanceolate and in Greater knapweed they are toothed.
In Europe, the plant is an important source of food for the European goldfinch. In central and southern Britain, the Six-spot Burnet Zygaena filipendulae is a common sight on the flowers of Common Knapweed, and is a firm favourite of our pollinating insects such as, honey bee, lime-speck pug moth, and the following butterflies: large skipper, meadow brown, small heath, painted lady, peacock, red admiral, small copper and small skipper, being a source of good quality nectar.
Greater Knapweed (Centaurea scabiosa)
Knapweeds are the jewels of our meadows and grasslands, growing up to 4 feet tall, with branched rough stiff stems and rayed purple flowers for weeks on end. Centaurea scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea, that is native to Europe, and can be easily distinguished from thistles by their lack of prickles.
Greater knapweed is a thistle-like plant that can be found on chalk downlands and dry rough grassland, roadside verges, woodland rides, hedgerows and clifftops. Scattered across the UK, but predominantly grows in England, it is more restricted in its distribution than its close relative, Common knapweed, being found in England mainly on chalky soils. It’s rarer in Wales and very sporadic in Scotland and Ireland, being absent even in areas with lime-rich soils.
It is a dark-green plant rather than the greyish-green of the similar Common Knapweed with medium to tall, robust, somewhat bristly plant to 1.5 metres. It has a thick, sturdy, grooved stem covered in soft hairs, with stems erect and branched above. The stems are angled in places, with reddish-brown ridges on the edges.
The deep green leaves are alternate, and with stalks. Usually pinnately lobed with oblong or linear segments. Unlike Common Knapweed the stem leaves are narrow with narrow side-lobes. Lower stem leaves are longer and with more narrow lobes which form a clump at the base, while the upper stem leaves are shorter and with fewer lobes.
The plant is sometimes confused with devils-bit scabious, however the leaves on this plant are arranged alternately, whereas in devils-bit they are opposite.
Like rayed versions of Common Knapweed but un-like Lesser Knapweed, the stems are swollen immediately below the dark spherical flower-bud. It is in bloom from June to September and the flowers emerge from very decorative fat, flagon-shaped buds that are clothed in grey-green scales that open into tassels of ragged bracts which form a crown around the central flowers pink petals upto 5cm across.The large, bright pink-purple 'flowers' of Greater Knapweed are actually composite flower heads made up of many small 'florets' (tiny flowers). The large, ragged, star-like ones sit around the edge of the flower head and are sterile, serving only to attract insects; while the smaller, densely packed florets in the middle are fertile. It is self fertile. As with many plants, albino versions exist too, but are not frequent. A white form, called ‘Albiflora’, is occasionally available, derived from a single plant discovered on a road verge in Pershore in 1980. It is not completely white; the petals are tinged slightly bluish-red whilst the stigmas are slightly yellowish-pink.
Generally pest-free and resistant to browsing by deer. This is the only known food plant for caterpillars of the Coleophoridae case-bearer moth Coleophora didymella. This species is very valuable to bees. It is also a magnet for many species of butterfly. Among them is the Marbled White, Painted Lady and Green-veined White, Common blues and Meadow browns, and is sometimes covered in these species, as well as moths, bees and hoverflies. The seed heads are likely to attract finches.
Greater Knapweed is the only host to Greater-Knapweed Broomrape (known just as Knapweed Broomrape). May be affected by powdery mildews