ORDER XXI. DROSERACEÆ—THE SUN-DEW TRIBE.
There are three genera in this tribe that are well known: Drosera, the Sun-dew; Dionæa muscipula, Venus’s Fly-trap; and Parnassia palustris, the Grass of Parnassus; all bog plants. The species of the genus Drosera are remarkable for the curious manner in which the leaves and peduncles are coiled up when they first appear, and in which they slowly unroll themselves as they grow. They are also beautifully edged with a sort of fringe of glandular red hairs, and a fluid exudes from these glands which makes them always appear as though covered with dew. The common Sun-dew (D. rotundifolia) is a British plant, with short roundish leaves; but other species are natives of New Holland and North America; and several of them have long slender leaves like threads. Venus’s Fly-trap (Dionæa muscipula) is a native of Carolina, in North America; the leaves are curiously formed of two lobes, which close and open as if hinged, and they are furnished with glandular hairs, which are so extremely irritable as to make the leaves close at the slightest touch, and thus to imprison any unfortunate insect that may be within the lobes. The petiole is so much dilated as to look like a leaf, but the real leaf consists of only the two roundish lobes edged with teeth that form the Fly-trap. The flowers are white, and they are produced in corymbs. The corolla has five petals, which do not fall off when they wither, but roll up so as to look like the cocoon of an insect.
ORDER XXII. POLYGALEÆ—THE MILKWORT TRIBE.
The genus Polygala is well known from the very handsome greenhouse plants which it contains. The flowers at first sight appear to resemble those of the Sweet Pea, having two wings like a standard, and a sort of keel; their construction is, however, very curious, and so complicated, as to be very difficult either to describe or to understand. The calyx is said by modern botanists to consist of five sepals, three of which are green and two lilac, these last being the part that resembles the standard of the Sweet Pea. The corolla is also said to consist of five petals, two of which stand erect, and the other three grow together to form the keel. The latter have their upper part cut into a kind of crest, like that of the Mignonette. Below the crest, the united petals form a kind of hood, under which are arranged the eight stamens, four on each side. The stamens themselves are as remarkable as the other parts of the flower; the filaments grow together into a thin kind of leaf, and each anther has but one cell, and opens by a pore at the apex. The pistil is also very curiously formed, as the style and stigma have the appearance of a gaping monopetalous corolla. The fruit is a flat two-celled capsule, which, when ripe, opens by two lips, separating from each other, and showing a seed within each cell. Even the seeds are not like other seeds, for each has a large white protuberance at one end, called a corancula.
ORDER XXIII. TREMANDREÆ.
Slender New Holland shrubs, with the habit of Heaths, rarely met with in British gardens.