The Dog Violet (_Viola canina_--Order _Violaceæ_) is probably too well known to need description, seeing that it is easily distinguished from the other species of the same genus by the absence of scent and by the presence of running stems. It is, however, very variable, both in its habits and habitats, so much so, indeed, that some botanists regard the varieties as distinct species under the titles of Wood Violet, Dark Wood Violet, Pale Wood Violet, Hill Violet, Bog Violet, &c. These different forms are distinguished by the shape of the leaves, which may be broadly-cordate, narrow-cordate, or lanceolate; and also by the nature of the stem and the form and colour of the spur of the corolla. In some the main stem is flowerless, but flowering stems proceed from the axils of its leaves; in others the main stem is long and branched, bearing flowers. The narrow-leaved and branched varieties occur principally on heaths, while the broad-leaved forms, in which the main stem is flowerless, are found chiefly in woods. The student will do well to compare as many forms as possible as an interesting study in variation. [Illustration: THE WILD COLUMBINE.] The flowers have five sepals; and five unequal petals, usually of a bluish-purple colour, the lower one prolonged backward into a blunt spur. Five stamens closely surround the ovary, which is composed of three carpels, but is one-celled. The mode of the dispersion of the seeds is particularly interesting in this instance. When the seeds are ripe the ovary splits into three valves which spread out till they are at right angles to their former position. Each valve is closely packed with smooth, oval seeds; and, as the carpels dry, their sides, originally convex, become gradually straightened so that they press on the seeds. The result is that the seeds are detached from the placenta, one by one, and suddenly shot out to a distance sometimes exceeding a yard. The whole process may be observed by placing some ripe fruits on a large sheet of paper spread in a warm, airy room. Another peculiarity of the violet is to be seen in its production of two distinct kinds of flowers. The spring flowers, which we know so well, are conspicuous, and are visited and pollinated by insects, but they produce few or no seeds. In the autumn another kind of flower is formed, inconspicuous ones that often possess no petals, and which do not open. These are fertilised by their own pollen, and produce abundance of seed. [Illustration: THE DOG VIOLET.]