Viola L.

Reference
Sp.Pl. 2:933 (1753)
Name Status
Current

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.

J. Gathe and Leslie Watson, 8 September 2016

Taxonomic Literature

  • Wheeler, Judy; Marchant, Neville; Lewington, Margaret; Graham, Lorraine (2002). Flora of the south west, Bunbury, Augusta, Denmark. Volume 2, dicotyledons. Australian Biological Resources Study. Canberra.
  • Grieve, B. J.; Blackall, W. E. (1998). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part II, Dicotyledons (Amaranthaceae to Lythraceae). University of W.A. Press. Nedlands, W.A.