Viola L.

Scientific Description

Common name. Violets. Family Violaceae.

Habit and leaf form. Herbs. Annual, or biennial, or perennial. Leaves basal, or cauline (more or less rosulate). Plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves. Mesophytic, or helophytic. Leaves alternate; spiral; petiolate; non-sheathing; simple; epulvinate. Leaf blades entire (usually), or dissected; ovate to orbicular (or subcircular); when dissected, pinnatifid; pinnately veined, or palmately veined; cross-venulate; cordate (deeply). Leaves with stipules. Stipules free of one another (more or less adnate to petiole); ovate-lanceolate, glandular, ciliate; persistent. Leaf blade margins entire (subentire), or crenate (and crenulate), or serrate. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present, or absent. Extra-floral nectaries present (gland-like or spur-like on back of 2 anterior anthers). Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers solitary; axillary; pedicellate; bracteate (K); (bi-) bracteolate; fragrant, or odourless; very irregular. The floral asymmetry involving the perianth, or involving the perianth and involving the androecium. Flowers 5 merous; cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; polysepalous (usually, more or less), or gamosepalous (at the base); imbricate; unequal but not bilabiate, or regular; basally appendaged; persistent; with the median member posterior. Sepals elliptic, or ovate. Corolla present; 5; 1 -whorled; polypetalous; imbricate (with descending aestivation); unequal but not bilabiate; white, or violet (or magenta); spurred (via the usually enlarged anterior member). Petals clawed, or sessile. Androecial members definite in number. Androecium 5. Androecial members free of the perianth; all equal; free of one another, or coherent; if coherent 1 - adelphous; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape; isomerous with the perianth; oppositisepalous (inserted below ovary); filantherous, or with sessile anthers. Anthers connivent (closely connivent around pistil); adnate; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged (anterior 2 anthers with basal appendages, nectary on back). Gynoecium 3 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary unilocular; 1 locular. The ‘odd’ carpel anterior. Ovary sessile. Gynoecium stylate. Styles 1; free. Stigmas 1; truncate (or appendiculate). Placentation parietal. Ovules in the single cavity 2–50 (many); arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent (elastically); a capsule. Capsules loculicidal and valvular. Fruit 3 celled; elastically dehiscent; 2–100 seeded (many). Seeds endospermic. Endosperm oily. Seeds winged, or wingless. Cotyledons 2 (flat). Embryo straight.

Economic uses, etc. Over 120 species of Viola are grown as ornamentals.

Etymology. From the Latin name of the violet.