The Heartsease is as variable as any of the other members of the genus, but whatever modifications of form it may present, it may always be readily distinguished from the other Violets by the general form of its foliage, which is much more cut up than in any of the other species and by the very large leafy stipules at the base of the true leaves. The stem, too, branches more than is commonly found in the other members of the genus. Besides the free branching of the stem, which is mostly 4 to 8 inches in height, it is generally very angular. The leaves are deeply cut into rounded lobes, the terminal one being considerably the largest. In the other species of Viola the foliage is ordinarily very simple in outline, heartshaped, or kidney-shaped, having its edge finely toothed. The flowers (1/4 to 1 1/4 inch across) vary a great deal in colour and size, but are either purple, yellow or white, and most commonly there is a combination of all these colours in each blossom. The upper petals are generally most showy in colour and purple in tint, while the lowest and broadest petal is usually a more or less deep tint of yellow. The base of the lowest petal is elongated into a spur, as in the Violet. The flowers are in due course succeeded by the little capsules of seeds, which when ripe, open by three valves. Though a near relative of the Violet, it does not produce any of the curious bud-like flowers - cleistogamous flowers - characteristic of the Violet, as its ordinary showy flowers manage to come to fruition so that there is no necessity for any others. Darwin found that the humble bee was the commonest insect visitor of the Heartsease, though the moth Pluvia visited it largely - another observer mentions Thrips small wingless insects - as frequent visitors to the flowers. Darwin considered that the cultivated Pansy rarely set seed if there were no insect visitors, but that the little Field Pansy can certainly fertilize itself if necessary. The flower protects itself from rain and dew by drooping its head both at night and in wet weather, and thus the back of the flower and not its face receives the moisture.