Composite Flowers

There are so many flowers of the order CompositÆ in bloom by the wayside and on waste ground during the summer months that we devote a chapter entirely to them.

This group is the largest of the natural orders, and is computed to contain about a tenth of all the known flowering plants. The chief distinguishing characteristic of the order is the arrangement of the flowers into crowded heads, each consisting of a number of little flowers or florets that are sessile on a common receptacle, as in the case of the Daisy, the Dandelion, and the Thistles.

The florets of each head or capitulum are generally arranged into two well-defined sets—the florets of the disc, occupying the centre; and the florets of the ray, spreading more or less in a radial manner from the edge of the disc. These two sets are often of different colours, as in the Daisy, where the disc florets are of a deep yellow, while the ray florets are white or pink.

In some of the Composites all the florets of each head are perfect, while in others some are perfect and some imperfect. Then, as regards the latter, they may be staminate or male florets, with no pistil; pistillate or female flowers, with no stamens; or neuter florets, possessing neither stamens nor pistil. In some few cases all the florets of one head are staminate, while the pistillate florets alone form other heads; and in these instances the two kinds of heads may be found on one plant, or only one kind may exist on the same plant. In all cases the capitulum is surrounded by one or more whorls of bracts which are often closely overlapping.

The florets seldom possess a distinguishable calyx, but there is sometimes an indication of the presence of five sepals; in many, however, the calyx is represented by a whorl of hairs on the summit of the ovary. Such a whorl is known as the pappus, and it frequently enlarges as the fruit ripens, forming a kind of parachute that allows the fruit to be carried great distances by the wind. The hairs of the pappus are often sessile on the fruit, but sometimes mounted on the summit of a slender stalk, as in the Dandelion. Further, the hairs which constitute the pappus may be simple or feathered.

The corolla frequently consists of five petals, united into a tube with as many teeth; but it is often ligulate or strap-shaped, in which case the presence of five petals is often denoted by five minute teeth at the tip.

Where stamens exist they are five in number, attached to the petals, and the anthers are generally united in such a manner that they form a tube within the tube of the corolla.

Fertilisation is brought about much in the same way in many of the composite flowers:—The anthers open inwards, discharging their pollen within the tube formed by themselves, and just above the stigma which, as yet, is immature. The style then lengthens, pushing its way up through the anther-tube, and brushing up the pollen by means of the tufts of hairs on its surface. At this stage a dense cluster of pollen cells, completely covering the top of the style, may be seen projecting above the tube of the corolla, and the pollen is sooner or later scattered, the distribution being aided greatly by the various insects which visit the flowers. The upper part of the style now divides into two parts, and the branches diverge, exposing the stigmatic surfaces which form the inner sides of the fork. It will thus be seen that the florets are not self-pollinated, since the stigma is generally mature after the pollen has all been removed from the same flower.

Our first example of this order is the Yellow Goat's-beard (Tragopogon pratensis), also known as Jack-go-to-bed-at-noon. This is a common wayside plant, of a glaucous green colour, with a milky sap. Its stem is erect, from one to two feet high, and the whole plant is smooth. The flower-heads are solitary, large, yellow, and surrounded by a single row of narrow bracts that are united below; and the peduncle is thickened at the top. The bracts are generally as long as the florets, and the latter usually close about the middle of the day. The fruit is long and narrow, with longitudinal ridges; and the pappus consists of rows of feathery hairs which interlock and form a very shallow cup. The flowers bloom during June and July.

The Bristly Ox-tongue (Helminthia echioides or Picris echioides), also a common plant, is more or less covered with rigid, hooked bristles, each of which arises from a swollen, white base; and it has a milky sap. The stem is stout, branched, very bristly, and grows from two to three feet high. The leaves are simple and toothed, the upper ones cordate and embracing the stem, and the lower ones auricled or eared. The heads are terminal, consisting of yellow, ligulate florets, surrounded by five large cordate bracts. The fruit is brown, curved, with transverse ridges and a stalked pappus of feathery hairs. This species flowers from June to September. It is shown on Plate III.

In the same genus we have the Hawkweed Picris (P. hieracoides) which bears yellow flowers from June to September. Its stem, more slender than that of the last species, is from two to three feet high, branched towards the top, and rough with hooked bristles; and the leaves are lanceolate and toothed. There are numerous heads of flowers, about an inch in diameter, usually arranged in a corymb, but sometimes in an umbel, and there are bracts on the peduncles.

The Strong-scented or Acrid Lettuce (Lactuca virosa) is moderately common on dry wastes. It is an acrid, glaucous, leafy and prickly plant, with a milky juice. Its erect stem grows to a height of three or four feet. Its leaves are spreading, obovate in form, with toothed margins, and bristly hairs on the under side of the midrib. The lower leaves are frequently marked with dark spots, and the upper ones have pointed auricles which clasp the stem. The heads of flowers are small, pale yellow, and arranged in a loose, spreading panicle. The bracts overlap, the outer ones being shorter, and the receptacle is flat. Each head contains only a few florets. The fruit is flattened, black, with a beak as long as itself and a pappus of many simple hairs. The flowers appear during July and August.

Another Lettuce, known as the Prickly Lettuce (L. Scariola), is somewhat rare. It is really less prickly than the last species, but is equally tall, and flowers during the same months. Its leaves are erect, lanceolate, sagittate, with a wavy margin; and the upper ones clasp the stem. The fruit of this species is of a greyish colour, and has a beak of the same length.

Two species of Sow-thistle (genus Sonchus) are included among our wayside Composites. They are erect, succulent plants, from two to three feet in height, with a milky juice, and either toothed or pinnatifid leaves. Their flower-heads are yellow, arranged in a corymb, and bloom during the whole of the summer. Each head is surrounded by several rows of overlapping bracts, and the receptacle is flat and pitted. The fruits are considerably flattened, without beaks; and the pappus consists of several rows of fine, silky, unbranched hairs.

One species is known as the Sharp-fringed Sow-thistle or the Common Milk-thistle (S. oleraceus). Its leaves are sometimes deeply divided, but always more or less toothed; and the teeth often terminate in sharp prickles. The upper ones clasp the stem, and have spreading, arrow-shaped ears. The stem is branched and hollow; and the fruit is ribbed and transversely wrinkled.

The second is the Common Sow-thistle (S. asper)—a very similar plant, but may be distinguished by its leaves, which are more spinously toothed, with rounded ears. In this one the fruits are also ribbed, but they are not wrinkled transversely.

The Smooth Hawk's-beard (Crepis virens) has a furrowed, branched stem, from a few inches to three feet in height. Its spreading radical leaves are deeply toothed, and narrower towards the base; and the stem leaves are narrow and sagittate. The numerous small heads of yellow flowers are panicled, and the outer florets are often tinged with red. The heads are surrounded by two rows of bracts, the outer of which are shorter and narrower, and the whole involucre assumes a conical form after flowering. The fruit is shorter than the pappus; tapering, but not beaked; and the pappus consists of several rows of unbranched, silky hairs. This plant flowers during July and August. It is very common on waste land, and may be frequently seen growing on old walls, and even on the roofs of country cottages and out-houses.

The genus Hieracium (Hawkweeds) is a puzzle not only to the beginner, but also to experienced botanists, who have not yet agreed as to its division into species. According to some authorities these latter amount to seven, but they, or rather some of them, are so variable, and present so many intermediate characters, that some botanists divide the British members into no less than thirty-three species.

All the plants of the group agree in the following particulars:—They have a milky sap. The leaves are nearly all radical. The flower-heads are either yellow or orange, surrounded by several rows of overlapping bracts. The receptacle is pitted. The fruit is not beaked, and its pappus consists of a single row of rigid, brittle, brownish hairs, which are simple and of unequal lengths.

One species at least is a common wayside flower, and this is the Shrubby Hawkweed (H. boreale). It grows from two to four feet high, and bears a corymb of many yellow heads, from July to September. Its stem is hairy below, downy with fine branched hairs above, and bears rigid, erect branches which are leafy, and often of a reddish colour. This species has no radical leaves. The stem leaves are ovate or lanceolate and toothed, the upper ones broad and slightly clasping the stem. The peduncle is scaly or woolly, and the involucre bracts are of a blackish green colour.

The Nipplewort (Lapsana communis) is another very common Composite of waysides and wastes. Its stem is erect, from one to two feet high, branched, armed with scanty stiff hairs below, and smooth above. The leaves are thin and usually hairy, the lower ones ovate, pinnatifid or coarsely-toothed, with a few smaller lobes along the stalks, and the upper ones small, and entire or only slightly toothed. The flower-heads are small, yellow, in a loose panicle with long slender stalks. The involucre consists of about eight glaucous scales, about a quarter of an inch in length, and a whorl of small outer ones. The fruits are flattened, with many longitudinal nervures, and have no pappus. The flowers may be seen from July to September.

The Chicory or Succory (Cichorium Intybus) is a local plant, but often very abundant where it exists. It has a long tap root; and a strong, erect, bristly and sticky stem. The lower leaves are spreading and hairy, deeply divided, with a large terminal lobe, and smaller lateral lobes which are pointed and coarsely toothed. The upper leaves are lanceolate, clasping the stem, with pointed auricles. The flower-heads are of a bright blue colour, large and conspicuous, mostly in sessile clusters of two or three along the rigid, spreading branches, but a few are terminal. The involucre consists of about eight inner bracts, and a whorl of outer ones that are much shorter. The florets are large; and the fruits are smooth, or nearly so, and closely enveloped in the lower part of the involucre. The time of flowering is from July to October.

Our next species is the Burdock (Arctium Lappa), familiar as a wayside plant not only on account of its abundance and its large size, but also on account of its globular flower-heads which cling so tenaciously to our clothing by means of the hooked points of the inner involucre bracts. It is a very stout, branching plant, varying from two to six feet in height, with very large, stalked, cordate lower leaves that often exceed a foot in length. The upper leaves are smaller, and broadly ovate; and both these and the lower ones are smooth or nearly so on the upper surface, but often covered with a short white down beneath. All the leaves are also finely toothed, but bear no prickles. The flower-heads are in terminal panicles, and are surrounded by many bracts which are either quite smooth or covered with a white, woolly down. The florets are purple, and all equal in size. The fruits are large, and bear a short pappus of stiff hairs.

We now come to the interesting group of Thistles, all distinguished by their very hard stems; their cut or toothed leaves, which are generally very prickly; and their round or oval heads of flowers, surrounded by many whorls of overlapping, and usually prickly, bracts. There are no ray florets, but all are tubular and approximately equal in length.

Our first example is the Welted Thistle (Carduus crispus or Carduus acanthoides), which is a common plant in the South of England, but much less abundant in the North. In general appearance it closely resembles the Musk Thistle (p. 266), but is usually taller. The stem is covered with prickles which run downwards in lines from the bases of the leaves. The flowers are purple, in small, globular, clustered heads, which droop slightly; and the numerous bracts of the involucre are narrow, more or less erect, and terminate in a spreading or hooked prickle. The pappus consists of rough, unbranched hairs. The above is the description of the commonest form of this thistle, but it is a very variable species. The plants vary from one to three feet in height, and flower from June to August.

Throughout the summer we may meet with the Spear Thistle (C. lanceolatus), a very abundant species which grows on almost all waste places. The plant is a stout one, varying from about one to five feet in height, with a winged, prickly stem. The leaves are cut into short, narrow lobes, with a long and pointed terminal one. They are covered above with stiff hairs, and below with a white down; and all the lobes terminate in stiff spines. The involucre is oval in form, covered with cottony down; and its bracts are lanceolate, terminating with a stiff, spreading spine. The flower-heads are few in number, with purple florets, and measure about an inch and a quarter in diameter.

Another common species is the Creeping Thistle (C. arvensis), which has a perennial, creeping rootstock that gives off erect annual stems from two to four feet in height. The stem is not winged, but the prickly leaves clasp it, and sometimes extend a little way down at their bases. The leaves are narrow, smooth, with edges turned inwards, very prickly, and cut into numerous narrow lobes. The flower-heads are small, arranged in loose terminal clusters, and are surrounded by numerous, closely-placed bracts with small, sharp points. The flowers are always imperfect, and the male and female blooms always occur on separate plants. The heads of the male plants are globular in form, with spreading purple florets; while those of the female plant are longer and almost cylindrical in form, with longer bracts and shorter florets. The pappus consists of numerous feathery hairs which grow very long as the fruit ripens. This species flowers during July and August.

The Tansy (Tanacetum vulgare) is common in the hedgerows of most localities, and is easily recognised by the powerful odour and bitter taste of its leaves and flowers. It has a creeping root; an erect, strong stem, which is either quite smooth or (generally) slightly downy; and large, pinnate leaves, with narrow, deeply-toothed or pinnatifid segments. There are a large number of flower-heads, nearly half an inch in diameter, of a bright yellow colour, and arranged in large flat-topped corymbs. This plant is common in most parts of Britain, grows to a height of about three feet, and flowers during August and September.

The Mugwort (Artemisia vulgaris) is a very common roadside plant in most districts, valued by many villagers as a remedy for rheumatism. It has a short, woody rootstock; and erect, branching stems varying from two to four feet in height. The leaves are deeply cut into narrow, acute segments which are either coarsely serrate or lobed. They are green and smooth above, but very white with a woolly down below. The flower-heads are very numerous, erect, and arranged in a somewhat crowded, long, terminal panicle. Each head is surrounded by a woolly involucre, and consists of from fifteen to over twenty florets, either all perfect or including a few without stamens. They are oval in form, and of a reddish or yellowish-brown colour. The plant blooms throughout the summer.

In the same genus is the Absinth or Wormwood (A. Absinthium), which is not so tall or so slender as the last species, from which it may readily be distinguished by its powerful aroma and bitter taste. The whole of the plant is whitish with a close, fine down; and the erect stems, from one to two feet high, are stiff and hard. The leaves are very similar to those of the Mugwort, but are much broader, are silky on both sides, and the narrow lobes of the leaves are blunt at the tips. The flower-heads are also similarly arranged, but they are almost globular in form, very silky, and more or less drooping. The florets are numerous, and of a dull yellow colour, the central ones being mostly fertile, while the outer, without stamens, are small, and often barren. The plant flowers during August and September, is not so common as the last species, but is abundant in districts near the sea.

One of the most conspicuous flowers of the summer is the Common Ragwort (Senecio JacobÆa). It belongs to the same genus as the Groundsel, but differs in having very showy, terminal corymbs of large, bright yellow flowers with spreading rays. Its erect stem does not branch, as a rule, except near the top, and reaches a height of from one to three or four feet. The outer bracts of the involucre are small and few in number, and both these and the inner ones are generally tipped with black. Occasionally we may meet with plants of this species in which the flower-heads have no ray, but in general the ray is well-formed, and consists of about twelve narrow or oblong florets.

The Common Feverfew (Matricaria Parthenium or Chrysanthemum Parthenium) is a very abundant wayside flower, of which a double variety is commonly grown in gardens. The plant reaches a foot or more in height, and flowers freely from July to September. The stems are erect and branched; and the leaves are stalked and pinnately divided into ovate or oblong, lobed, toothed segments. The numerous flower-heads are arranged in a corymb, and are about half an inch in diameter, with white ray and yellow disc. The plant may be distinguished from similar species of the same genus by the little toothed border on the summit of the ripe fruits, and by the strong and somewhat pleasant odour of all its parts.

Even more common, in most places, is the Corn Feverfew or Scentless Mayweed (M. inodora), which flowers from June to the end of the summer. Its stem is erect, with spreading branches; and the sessile leaves are two or three times divided into narrow, almost hair-like segments. The flower-heads are much larger than those of the last species, sometimes reaching a diameter of about two inches, and are solitary. The involucre is brown, with a membranous edge; the ray white, and the disc yellow. It is sometimes confused with the Wild Chamomile, but may be distinguished by the shape of the receptacle, which is hemispherical, and not so conical as in Chamomilla.

Our last example of the Composites of the wayside is the Yarrow or Milfoil (Achillea millefolium)—a plant that might be mistaken by the beginner for one of the Umbellifers when seen at a distance; but a closer examination will show not only that the level-topped inflorescence is a dense, terminal corymb, but also that the flowers are collected into little heads, each of which consists of a few white or pink, pistillate ray-florets, surrounding a little cluster of tubular, perfect, yellow florets of the disc. The leaves are narrow oblong, and very finely cut into many hair-like, branching segments. The whole plant has a strong and rather pleasant odour. It grows from six to eighteen inches high, and flowers from June to September.