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 Yellow Goat's-Beard.
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 Hawkweek Picris.
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.