Hyptis Jacq.

Scientific Description

Common name. Hyptis. Family Lamiaceae.

Habit and leaf form. Herbs, or shrubs (sub-); evergreen; bearing essential oils. Plants unarmed. Annual, or perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems tetragonal. Stem internodes solid, or hollow. To 0.5–2 m high. Self supporting, or climbing. Leaves small to medium-sized; not fasciculate; opposite; not decurrent on the stems; ‘herbaceous’; not imbricate; petiolate; aromatic, or foetid; simple; epulvinate. Leaf blades entire; flat; triangular to obtriangular (broadly); pinnately veined; cross-venulate; cordate to cuneate at the base, or rounded at the base. Mature leaf blades adaxially sparsely pilose; abaxially pubescent. Leaves without stipules. Leaf blade margins irregularly and densely serrate; flat. Leaves without a persistent basal meristem. Leaf anatomy. Hairs present; 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. Entomophilous, or ornithophilous; via hymenoptera, or via lepidoptera, or via diptera.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered. Flowers in verticils. The terminal inflorescence unit cymose. Inflorescences not scapiflorous; terminal, or axillary; lax 2–5-flowered secund monochasial cymes, arranged racemosely towards the ends of branches in axils of smaller leaves. Flowers pedicellate; bracteate; ebracteolate; minute to medium-sized; somewhat irregular to very irregular; zygomorphic. The floral asymmetry involving the perianth and involving the androecium. Flowers cyclic; tetracyclic. Floral receptacle developing a gynophore, or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present, or absent. Perianth with distinct calyx and corolla; 4–10; 2 -whorled; isomerous, or anisomerous (or only dubiously interpretable). Calyx present; 5; 1 -whorled; gamosepalous; toothed (teeth erect, subequal, acute or awn-like); prominently 10 veined; erect; imbricate, or open in bud; more or less equalling the corolla, or exceeding the corolla; campanulate, or tubular; regular (the members sub-equal); non-fleshy; persistent; with the median member posterior. Corolla present; disguisedly 5; 1 -whorled; gamopetalous; imbricate; bilabiate (the abaxial lip 3-lobed with the middle one bent abruptly downwards, the adaxial lip 2-lobed, shorter than the abaxial lip and erect, spreading or reflexed); plain; blue to violet, or purple to blue, or blue. Corolla members entire. Androecium present. Fertile stamens present. Androecial members definite in number. Androecium 4. Androecial members adnate (inserted at mouth of corolla); markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 4. Staminal insertion in the throat of the corolla tube. Stamens 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. 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 pistil 4 celled. Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular, or 4 locular. Locules secondarily divided by ‘false septa’. Gynoecium median; stylate. Styles 1; simple; from a depression at the top of the ovary; ‘gynobasic’. Stigmas 2, or 1; 2 - lobed (or subentire). Placentation basal. Ovules 2 per locule, or 1 per locule; ascending; apotropous; non-arillate; anatropous, or hemianatropous.

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

Special features. The flowering nodes separated by extended internodes. 3–10 flowers subtended by each floral leaf. Calyx limb 5 lobed. Corolla tube exceeding the calyx, or not exceeding the calyx. The upper lip of the corolla incorporating 2 members, the lower 3, or incorporating 4 members, the lower 1; (posterior, adaxial) lip of the corolla bilobed. Lower (abaxial) lip of the corolla 3 lobed (the middle one bent down). Stamens descending.

Geography, cytology, number of species. Adventive. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. A genus of more than 300 species; 1 species in Western Australia; 0 endemic to Western Australia.