VIOLET  . The violets comprise a large botanical genus (

Viol)—in which more than 200 species have been described —found principally in temperate or mountain regions of the northern hemisphere; they also occur in mountainous districts of South America and South and Tropical Africa, while a few are found in Australasia . The species are mostly low-growing herbs with alternate leaves provided with large leafy stipules (fig . I) . The flowers, which are solitary, or rarely in pairs, at the end of slender axillary flower-stalks, are very irregular in form, with five sepals prolonged at the base, and five petals, the lowest one larger than the others and with a spur, in which collects the honey secreted by the spurs of the two adjoining stamens . The five anthers are remarkable for the coloured processes which extend beyond the anther cells and form a sort of cone around the style (fig . 2) . The ovary is superior and one-celled, with three parietal placentas and numerous ovules; it bears a single style, which ends in a dilated or hood-like stigma (fig . 3) . The fruit is a capsule bursting loculicidally,i.e. through the centre of each of the three valves . By the contraction of the valves the small smooth seeds, which form a row down the centre, are shot out to some little distance from the parent plant . The irregular construction of the flower is connected with fertilization by insect agency .

To reach the honey in the spur of the flower, the insect must thrust its

proboscis into the flower close under the globular head of the stigma . This lies in the anterior part of a groove fringed with hairs on the inferior petal . The anthers shed their pollen into this groove, either of themselves or when the pistil is shaken by the insertion of the bee's proboscis . The proboscis, passing down this groove to the spur, becomes dusted with pollen; as it. is drawn back, it presses up the lip-like valve of the stigma so that no pollen can enter the stigmatic chamber; but as it enters the next flower it leaves some pollen on the upper surface of the valve, and thus cross-fertilization is effected . In the sweet violet, V. odorata and other species, inconspicuous permanently closed or "cleistogamic" flowers (fig . 4) occur of a greenish colour, so that they offer no attractions to insect visitors and their form is correspondingly regular . The anthers are so situated that the pollen on escaping comes into contact with the stigma; in such flowers self-fertilization is compulsory and very effectual, as seeds in profusion are produced . Several species of Viola are native to Great Britain . Viola canina (fig . 5) is the dog violet, many forms or subspecies of which are recognized; V. odorata, sweet violet, is highly prized for its fragrance, and in cultivation numerous varieties have originated . The Neapolitan or Parma violet (var. pallida plena) is a form with very sweet-scented, double, pale lavender flowers; var. sulphurea has shining deep green leaves and lemon-yellow flowers, deeper yellow in the centre, and with a pale-violet spur . Sweet violets like a rich, fairly heavy soil, with a north or north-west aspect if possible; F?G .

4.-CleistogamicFlower of Viola sylvatica . I . Flower . 2 . Flower more highly magnified and cut open. a, anther; s, pistil; st, style; v, stigmatic surface . they are readily increased by dividing the crowns after flowering . Other species known in gardens are: V. altaica, flowers yellow or i . Floral

diagram of Viola, showing arrangement of parts in horizontal plan. b, pair of bracteoles below the flower; s, sepals; p, petals; st, stamens; o, ovary . 2 . Fruit, split open . violet with yellow eye; V. biflora, a pretty little species 3–4 in. high with small yellow flowers, the large petal being streaked with black; V. calcarata, flowers light blue or white, or yellow in var . "lava; V. cornuta, flowers pale blue—there are a few good varieties of this, including one with white flowers; V. cucullata, a free-flowering American species with violet-blue or purple flowers; V .

Munbyana, a native of

Algeria, with large violet or yellow flowers; V. pedata, the bird's-foot violet, with pedately divided leaves and usually bright blue flowers; V. rothomagensis, a native of western Europe, with flowers bright blue striped with black, and sometimes called the Rouen violet; and V. suavis, a native of Asia Minor, the Russian violet, with pale-blue sweet-scented flowers . The garden pansies or heartseases are derivatives from V. tricolor, a cornfield weed, or V. al:aice, a native of the Altai mountains . (See PANSY.) " Bedding violas," which differ from pansies in some slight technical details, have been raised from V. cornuta and V. lutea by crossing with the show pansies . The application of an infusion of violet leaves was at one time believed to have the power of reducing the size of cancerous growths, but its use is now discredited .