Endostemon N.E.Br.

Lamiaceae (Labiatae), A.J. Paton, G. Bramley, O. Ryding, R.M. Polhill, Y.B. Harvey, M. Iwarsson, F. Willis, P.B. Phillipson, K. Balkwill, C.W. Lukhoba, D.F. Otieno, & R.M. Harley. Flora of Tropical East Africa. 2009

Habit

Aromatic annual or perennial herbs, woody herbs or suffrutices

Stem

Stems sometimes prostrate, usually erect, branching above, woody at base

Leaves

Leaves opposite

Flowers

Flowers hermaphrodite, arranged in 2–6-flowered verticils in a lax inflorescence; bracts small, sometimes forming an inconspicuous apical coma

Calyx

Calyx persistent, spreading, ascending or downward-pointing, shortly tubular or tubular-campanulate, bilabiate; posterior lip ovate, decurrent; anterior lip 4-lobed; fruiting calyx with posterior lip accresent; throat open, glabrous, anterior lip with 4 lanceolate lobes, the median pair longer than the lateral pair, or throat glabrous, closed by the convergent linear, obliquely truncate to rounded lateral lobes and the lanceolate median lobes of the anterior lip being pressed against the posterior lip, or throat closed with a ring of dense, villose hairs, anterior lip with lanceolate to deltate lateral lobes and linear, slightly cucullate median lobes

Corolla

Corolla white, pink, purple or bluish, slightly bilabiate, 4-lobed with the posterior lobe sometimes emarginate or bifid; tube straight, dilating at throat, villose where stamens adnate

Stamens

Stamens 4, declinate, held within the corolla; filaments free, very short, villose, adnating to the corolla throat or just below, regularly spaced, not all together on the anterior side of the throat; anthers dorsifixed, synthecous, thecae convergent

Disc

Disk equally 4-lobed

Ovary

Ovary glabrous or pubescent at apex, deeply 4-lobed; style gynobasic with a basal swelling just above the nutlets, stigma capitate with lobes rounded and adpressed

Fruits

Nutlets black or brown, ovoid or narrowly ovoid, apex rounded or truncate, smooth with a small basal scar, producing a lot or a small amount of mucilage when wet; embryo straight, exalbuminous.

Note

The genus is divided into four sections, three of which occur in East Africa, see Paton et al., loc. cit (1994). Sect. Leucosphaeri A. Paton, Harley & M.M. Harley (Fig. 31: 5–6, p. 197) is found in Ethiopia and Somalia.