Prunella L.

Scientific Description

Family Lamiaceae.

Habit and leaf form. Herbs; evergreen; bearing essential oils. Plants unarmed. Perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems tetragonal. To 0.05–0.3 m high. Leaves small to medium-sized; not fasciculate; opposite; not imbricate; petiolate; aromatic, or without marked odour; simple; epulvinate. Leaf blades entire; flat; ovate; pinnately veined; cross-venulate; cordate to cuneate at the base, or rounded at the base. Leaves without stipules. Leaf blade margins entire, or dentate; flat. Leaves without a persistent basal meristem. Leaf anatomy. Glandular hairs present. Urticating hairs absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous. Entomophilous, or ornithophilous; usually via hymenoptera, or via lepidoptera, or via diptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in verticils. The terminal inflorescence unit cymose. Inflorescences terminal; terminal, cylindrical, spike-like, 3-to mostly 6-flowered in the axil of bracts. Flowers sessile; bracteate; small; very irregular; zygomorphic; cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Perianth with distinct calyx and corolla; 4–10; 2 -whorled; isomerous, or anisomerous. Calyx present; 5; 1 -whorled; gamosepalous; blunt-lobed, or toothed (ciliate); imbricate, or open in bud; exceeded by the corolla; campanulate, or funnel-shaped, or tubular; bilabiate (lower lip deeply bilobed, upper lip truncate with 3 sharp, almost obsolete toothlike lobes); non-fleshy; persistent; with the median member posterior. Calyx lobes linear, or ovate (lower lip). Corolla present; disguisedly 5; 1 -whorled; gamopetalous; blunt-lobed; imbricate; bilabiate (the lower lip spathulate with 2 narrow lateral lobes and a broad-spathulate medial lobe, the upper lip broad-oblong and shallowly 2-lobed); plain; deep purple to blue. Corolla members entire. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 4. Androecial members adnate; markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4; becoming exserted; didynamous; all more or less similar in shape; reduced in number relative to the adjacent perianth; fertile stamens representing the posterior-lateral pair and the anterior-lateral pair; oppositisepalous; all alternating with the corolla members. Filaments filiform. Anthers connivent, or separate from one another; dorsifixed; versatile, or non-versatile; dehiscing via longitudinal slits; introrse; unilocular to bilocular; tetrasporangiate; unappendaged. Pollen shed as single grains. Fertile gynoecium present. Gynoecium 2 carpelled (the carpels deeply lobed to mimic G4). The pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular (originally), or 4 locular (by intrusions of the ovary wall constituting ‘ false septa’). Locules secondarily divided by ‘false septa’. Gynoecium median; stylate. Styles 1; simple; from a depression at the top of the ovary (the ovary deeply 4-lobed); ‘gynobasic’; becoming exserted. Stigmas 2, or 1 (by reduction); 2 - lobed. Placentation basal. Ovules 2 per locule, or 1 per locule (two per original loculus, but one per locellus); ascending; apotropous; non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit non-fleshy, or fleshy; a schizocarp. Mericarps (2–)4; comprising nutlets. Seeds endospermic to non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo straight.

Special features. The flowering nodes aggregated in dense heads, or aggregated in dense spicate inflorescences. (2–)3(–4) flowers subtended by each floral leaf. Calyx limb 5 lobed. Upper lip of calyx lobed; 3 lobed. Lower lip of calyx lobed; 2 lobed. Corolla tube slightly exceeding the calyx. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla entire, or bilobed (or toothed). Lower (abaxial) lip of the corolla 3 lobed.

Geography, cytology, number of species. Adventive. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. A genus of 7 species; 1 species in Western Australia; 0 endemic to Western Australia.

Etymology. Possibly from the Latin for "purple", referring to the flowers or from the German Brane (quinsy) which they were said to cure.