Leucas glabrata (Vahl) Sm.

J. R. Timberlake, E. S. Martins (2013). Flora Zambesiaca, Vol 8: part 8. Royal Botanic Gardens, Kew

Type

Types: Yemen, Forsskål 217 (C syntype); Yemen, Forsskål 222 (C syntype).

Morphology General Habit

Perennial subshrub from a woody rootstock, with ascending stem forming an erect loosely branched bush, or herb (occasionally annual) with multiple stem, either form occasionally straggling over other vegetation, 0.3–1.8 m high

Morphology Stem

Stems sharply quadrangular, occasionally with dark coloration on angles, subglabrous to pubescent with retrorse (occasionally antrorse) hairs, occasionally with yellow sessile glands or glandular hairs

Morphology Leaves

Leaves shortly to distinctly petiolate; blade 0.7–9 × 0.3–0.5 cm, narrowly ovate to ovate or occasionally ± lanceolate, margins serrate to crenate-serrate, apex acute or rounded, base rounded, upper surface sparsely to evenly pubescent with usually appressed hairs, hairs occasionally with enlarged bases appearing hispid, sometimes venation appearing impressed, lower surface as upper, although hairs can be plentiful on often raised venation, with yellow sessile glands; petiole 4–25 mm long, with short eglandular or occasionally glandular hairs

Morphology Reproductive morphology Inflorescences

Inflorescence of (2)6–8 verticils spaced 7–55 mm apart, 6–8(12) flowers per verticil; pedicel 1–2(20) mm long, with similar short hairs; bracteoles subulate, 1.5–3(6) mm long, with similar short hairs

Morphology Reproductive morphology Flowers Calyx

Calyx funnel-shaped, tube 7.5–11 mm long at anthesis, not noticeably expanding in fruit, pubescent with appressed hairs especially on vein ridges, with yellow sessile glands, inner surface with short hairs; throat asymmetric, anterior lip 1–3 mm longer than posterior; lobes 10, narrowly triangular to triangular, often becoming subulate, anterior 3 lobes on ± 1 mm extension of tube, 1.5–2 mm long, other lateral and posterior lobes 2–3 mm long

Morphology Reproductive morphology Flowers Corolla

Corolla with white hairs, 9–16 mm long; tube 6.5–9 mm long, outer surface pubescent becoming glabrous in lower half, inner surface with slightly undulate band of glandular hairs halfway down tube; posterior lip 5–7.5 mm long; anterior lip 4–7.5 mm long, inner surface with short hairs at inner side of lateral lobes, pointing towards sinus between lateral and centre lobe, outer surface pubescent except towards lobe margins

Morphology Reproductive morphology Fruits

Nutlets 1–2(2.7) × (0.3)1–1.3 mm, conspicuously warty, eglandular.

Distribution

Botswana, Zambia, Zimbabwe, Malawi, Mozambique. Also in Yemen, Saudi Arabia, Sudan, Ethiopia, Somalia, Uganda, Kenya, Tanzania, Namibia and South Africa.

Ecology

In a variety of habitats from damp ground in riverine alluvial plains to inselbergs and termite mounds, in grassland, mixed deciduous woodland or bushland, on stony soil, black cotton soil, red lateritic soil or dark loam; 25–1450 m.

Conservation

Widespread; Least Concern.

Recognition

Leucas glabrata is a widespread taxon varying especially in its habit and leaf morphology. All forms are united, however, by the sharply angled square stem and by all features of the inflorescence except size. Leaves vary greatly in shape and size, but this seems partly correlated to habitat – in shady areas plants tend to have larger leaves, are taller and less branched, but in more open places such as grassland and disturbed areas plants have much smaller leaves, woodier stems (perhaps due to grazing pressure) and are more branched.

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. Leucas, G. Bramley. Flora of Tropical East Africa. 2009

Type

Types: Yemen, Forsskål 217 (C-Forssk., syn.) & 222 (C, syn.)

Morphology General Habit

Perennial subshrub from a woody rootstock, with ascending stems forming an erect loosely branched bush, or herb (occasionally annual) with multiple stems, either form occasionally straggling over other vegetation, 0.3–1.8 m high

Morphology Stem

Stems sharply quadrangular, occasionally with dark coloration at the angles, subglabrous to pubescent with downward-pointing (occasionally upward pointing) hairs, also occasionally with yellow sessile glands or glandular hairs

Morphology Leaves

Leaves shortly to distinctly petiolate; blades narrowly ovate to ovate or occasionally ± lanceolate, 0.7–9 × 0.3–0.5 cm, margin serrate to crenate-serrate, apex acute or rounded, base rounded, upper surface sparsely to evenly pubescent with usually appressed hairs, the hairs occasionally with enlarged bases appearing hispid, sometimes the venation appearing impressed, lower surface as upper although hairs can be more plentiful on the venation which is often raised, also with varying amounts of yellow sessile glands; petioles 4–25 mm long, with short eglandular or occasionally glandular hairs

Morphology Reproductive morphology Inflorescences

Inflorescence of (2–)6–8 verticils spaced 7–55 mm apart; 6–8(–12) flowers per verticil; pedicels 1–2(–20) mm long, with short eglandular downwardpointing or glandular hairs; bracteoles subulate, 1.5–3(–6) mm long, with short downward-pointing eglandular or occasionally glandular hairs

Morphology Reproductive morphology Flowers Calyx

Calyx funnelshaped, tube 7.5–11 mm long at anthesis, not noticeably expanding in fruit, pubescent with appressed hairs especially on the vein ridges, also with yellow sessile glands, inner surface with short hairs; throat asymmetric, the anterior lip 1–3 mm longer than the posterior; lobes 10, narrowly triangular to triangular, often becoming subulate, the anterior three lobes on a ± 1 mm extension of the tube then 1.5–2 mm long, the other lateral and posterior lobes 2–3 mm long

Morphology Reproductive morphology Flowers Corolla

Corolla with white hairs, 9–?18 mm long; tube 6.5–9 mm long, outer surface pubescent becoming glabrous in the lower half, inner surface with a slightly undulate band of glandular hairs halfway down the tube; posterior lip 5–7.5 mm long; anterior lip 4–7.5 mm long, inner surface with short hairs at the inner side of the lateral lobes, pointing towards the sinus between the lateral and centre lobe, outer surface pubescent except towards the lobe margins

Morphology Reproductive morphology Fruits

Nutlets 1–2(–2.7) × (0.3–)1–1.3 mm, conspicuously warty, eglandular

Figures

Fig 12: 5-9, p 66

Ecology

Found in a variety of different habitats, from damp ground in riverine alluvial plains to dry lava outcrops, on inselbergs and termite mounds, in grassland, mixed dry bushland to mixed deciduous woodland, both in shade or in direct sunlight, and in stony soil, amongst granites, black cotton soil, red lateritic soil or in dark loam; 20–2100(–2700) m

Conservation

Least concern; widely distributed

Note

In K 1 there is one specimen, Gilbert & Thulin 1130 from Wajir, with considerably longer pedicels than all others (to 20 mm long as opposed to 1–2 mm long). Occasionally bracteoles can be longer than typical (up to 6 mm), especially in T 3, e.g. Hedberg 6913 from Same and Faulkner 980 from Magunga Estate, Korogwe. Leucas glabrata is a widespread taxon, varying especially in its habit and leaf morphology. All forms are united, however, by the sharply angled square stem and by all features of the inflorescence, with the exception of variation in size. Leaves vary greatly in shape and size and this seems to be partly correlated to habitat: in shady areas such as woodland, the plants tend to have larger leaves, are taller and less branched, but in more open areas such as grassland and disturbed areas the plants have much smaller leaves, woodier stems (perhaps as a result of grazing pressure) and are more branched. Leaves can be very tiny, e.g. 7 × 3.5 mm on Greenway, Turner & Harvey 10543. In T 3 there are plants with largish ± lanceolate leaves, e.g. Faulkner 980, 4034 and Archbold 127. Sebald’s var. chiatelliniana, known only from the Somalian type and one collection from K 7, and L. schliebenii Sebald, known only from the type, are reduced to synonymy on the basis that they share all characters with the variable L. glabrata.

Distribution

Flora districts: U1 U3 K1 K2 K3 K4 K5 K6 K7 T1 T2 T3 T5 T6 T7 T8 Range: Rwanda, Sudan, Eritrea, Ethiopia, Somalia, Zambia, Malawi, Mozambique, Zimbabwe, Botswana, Namibia and South Africa, also in Yemen and Saudi Arabia

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Type

S3, “Chisimaio”, Senni 530 (FT holo.)

Distribution

S3 - The type is the only typical collection from Somalia. Kenya

Ecology

Low altitude.