In all these points the Heartsease and the Violet are alike; but they differ materially in the leaves, which in the Violet are broad and heart-shaped, without stipules; but in the Heartsease are small and ovate, with such very large and deeply-cut stipules, that they are by most persons mistaken for the leaves. I may here be asked what are stipules, and in what do they differ from leaves? In answer to the first question, I can only inform my readers that stipules are generally little leaf-like bodies, which seem to act as attendants upon leaves, as bracts seem to wait upon flowers; but in what they differ from leaves, except in size and shape, I have not been able to learn. Even Dr. Lindley in the last edition of his Introduction to Botany, says, “What stipules really are is not well made out.” The Heartsease and the Violet differ also in their habit of growth. The Violet is a creeping plant with no stalks but those supporting the flowers, while the Heartsease stands erect, with a thick square stem, so strong, that, notwithstanding its succulent nature, it may be trained like a little tree. 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.