Two species of Willow Herb (order _Onagraceæ_) grow in copses and thickets, and are easily recognised by their rose-coloured flowers with very long, inferior ovaries. One is the beautiful French Willow or Rose Bay Willow Herb (_Epilobium angustifolium_), an erect plant, varying from two to six feet in height, widely distributed, though not very common, flowering during July and August. Its leaves are alternate, narrow-elliptical, entire or with very small teeth, and very shortly stalked. The flowers are about an inch in diameter, numerous, forming a very long, loose, terminal, tapering raceme, with a narrow bract at the base of each pedicel. The calyx is tubular, four-cleft, attached to the top of the long ovary; the corolla consists of four entire, nearly equal, spreading petals; the stamens, eight in number, all bend downwards; and the stigma is deeply divided into four lobes, on a long style which also bends downward. The fruit is a four-celled capsule, two or three inches long, which splits when ripe, its valves curling downwards and exposing numerous minute seeds, each of which has a silky tuft of fine hairs that enables it to be dispersed by the wind. The plant is most frequently seen in damp copses, and among the undergrowth of damp woods.
The second species is the Pale Smooth-leaved Willow Herb (_E. roseum_), an erect plant, seldom more than two feet high, found principally in the damp copses of the southern counties, flowering in July and August. Its stem is four-angled, two opposite angles being much more prominent than the other two; and its leaves are opposite, with longer stalks, lanceolate or elliptical, pointed, toothed, smooth, usually about two inches long. The flowers are not nearly so numerous as those of the last species, are only a little over a third of an inch in diameter, and in a short, leafy panicle, drooping while in the bud. The calyx is deeply divided into four sepals about a sixth of an inch long; the corolla consists of four notched petals, a little longer than the sepals; the stamens, ovary, fruit, and seeds correspond in number and character with those of the last species; but the stigma is either entire or divided into four very short lobes.