Coleus sylvestris (Gürke) A.J.Paton & Phillipson

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

Type

Type: Tanzania, Kilimanjaro, Kifinika Hill on Mawenzi, Volkens 965 (B†, holo. BM!, G!, iso.)

Morphology General Habit

Aromatic soft-wooded shrub or herb, 0.5–3 m tall

Morphology Stem

Stems erect or scandent, often purplish toward apex and purple-spotted below, quadrangular, branching, subglabrous or with adpressed hairs below, becoming densely pubescent above with short patent, often coloured, glandular or eglandular hairs and with pale sessile glands

Morphology Leaves

Leaves ascending or spreading, petiolate; blades ovate, 4–12 × 2–7 cm, crenate or serrate, sometimes weakly revolute, apex acute or acuminate, base cuneate to truncate, attenuate at petiole, densely to sparsely pubescent, with pale sessile glands which are sometimes slightly sunken; petiole 15–70 mm long

Morphology Reproductive morphology Inflorescences

Inflorescence terminal and axillary with (2–)4–12(–14)-flowered verticils up to 20 mm apart, with bracts subtending 1–5(–7) flowers arranged in opposite or subopposite sessile cymes which sometimes bear 1 or 2 small leaf-like scales at the base; bracts ovate, 1–2 mm long; pedicels 6–15 mm long in fruit

Morphology Reproductive morphology Flowers Calyx

Calyx 1.5–4.5 mm long, sparsely pubescent with pale yellowish glands; fruiting calyx, 6–10 mm long, tubular, slightly curved with pedicel attached centrally at calyx base or excentrically; throat truncate; posterior lip lanceolate or ovate, acuminate at apex, decurrent, curving upwards; lobes of anterior lip lanceolate, median longer than lateral, curving upwards

Morphology Reproductive morphology Flowers Corolla

Corolla blue or more rarely white, 9–18 mm long, sparsely pubescent with longer hairs on margin of anterior lip and with scattered pale sessile glands; tube 6–8 mm long,sigmoid; posterior lip much shorter than anterior; anterior lip (5–)6–10 mm long, horizontal, deeply cucullate enclosing stamens

Morphology Reproductive morphology Flowers Androecium Stamens

Staminal filaments fused at base, posterior soon free, anterior fused for a longer distance than posterior

Morphology Reproductive morphology Fruits

Nutlets brown with darker, slightly raised speckles, ovoid, slightly flattened, 1.5 mm long, not producing obvious mucilage.

Ecology

Montane forest, often in bamboo or Hagenia zones; 1700–3300 m, down to 1250 m in T 2

Conservation

Least concern; widely distributed

Note

Very close to P. dolichopodus Briq. from South Africa, Malawi and Zimbabwe but this differs in having free, rather than shortly fused staminal filaments, and corollas shorter than 10 mm. P. dolichopodus tends to be a shorter plant growing up to 1.2 m tall. May also be confused with P. defoliatus which usually is leafless when flowering, has shorter pedicels (less than 5 mm long in fruit), and a narrower posterior lip of the calyx. Ward 933 from Idode, Tanzania ( T 7), approaches P. garckeanus (Vatke) J.K.Morton, a related species from Ethiopia. P. garckeanus differs in having pedicels 15–18 mm long and a longer fruiting calyx (11–22 mm long). Can also be confused with P. alpinus which has very obvious red, rather than pale, sessile glands on the flowers and stem. Other differences include P. sylvestris having a longer fruiting calyx (6–10 mm rather than 4–6 mm long), the corolla tube dilates more gradually in P. sylvestris and the corolla tube is ± equal in length to the anterior lip, whereas in P. alpinus the tube is usually shorter than the anterior lip.

Distribution

Range: Nigeria, Cameroon, Congo-Kinshasa, Rwanda, Ethiopia, Eritrea, Zambia, Malawi and Madagascar Flora districts: U2 U3 K1 K2 K3 K4 K5 K6 T2 T3 T 4 , T6 T7

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

Type

Type: Tanzania, Kilimanjaro, Rifinika Hill on Mawenzi, 14.ix.1893, Volkens 965 (B† holotype, BM, G).

Morphology General Habit

Perennial soft-wooded shrub or herb 0.5–3 m tall; aromatic- Stems erect or scandent, often purplish toward apex and purple-spotted below, quadrangular, branching, subglabrous or with adpressed hairs below, becoming densely pubescent above with short spreading, often coloured, glandular or eglandular hairs and pale sessile glands

Morphology Leaves

Leaves ascending or spreading, petiolate; blade 40–120 × 20–70 mm, ovate, crenate or serrate, sometimes weakly revolute, apex acute or acuminate, base cuneate to truncate, attenuate at petiole, densely to sparsely pubescent, with pale sessile glands sometimes slightly sunken; petiole 15–70 mm long

Morphology Reproductive morphology Inflorescences

Inflorescences terminal and axillary with (2)4–12(14)-flowered verticils up to 20 mm apart, bract subtending 1–5(7) flowers arranged in opposite or subopposite sessile cymes, sometimes with 1 or 2 small leaf- like scales at base; bract 1–2 mm long, ovate; pedicel 6–15 mm long in fruit

Morphology Reproductive morphology Flowers Calyx

Calyx 1.5–4.5 mm long, sparsely pubescent, with pale yellowish glands; fruiting calyx 6–10 mm long, tubular, slightly curved, pedicel attached centrally at calyx base or eccentrically; throat truncate; posterior lip lanceolate or ovate, acuminate at apex, decurrent, curving upwards; lobes of anterior lip lanceolate, median longer than lateral, curving upwards

Morphology Reproductive morphology Flowers Corolla

Corolla blue or more rarely white, 9–18 mm long, sparsely pubescent with longer hairs on margin of anterior lip, with scattered pale sessile glands; tube 6–8 mm long, sigmoid; posterior lip much shorter than anterior; anterior lip (5)6–10 mm long, horizontal, deeply cucullate, enclosing stamens

Morphology Reproductive morphology Flowers Androecium Stamens Filaments

Staminal filaments fused at base, posterior soon free, anterior fused for longer distance than posterior

Morphology Reproductive morphology Fruits

Nutlets brown with darker, slightly raised speckles, 1.5 mm long, ovoid, slightly flattenend; not producing obvious mucilage.

Distribution

Zambia, Malawi. Also in Nigeria, Cameroon, Congo, Rwanda, Ethiopia, Uganda, Kenya, Tanzania and Madagascar.

Ecology

Evergreen forest; 1650–2200 m.

Conservation

Widespread; Least Concern.

Recognition

Very close to Plectranthus dolichopodus which differs in having free rather than shortly fused staminal filaments and corollas shorter than 10 mm. P. dolichopodus also tends to be a shorter plant to 1.2 m tall. Can also be confused with P. alpinus which has very obvious red not pale sessile glands on the flowers and stem. Other differences include P. sylvestris having a longer fruiting calyx (6–10 mm vs. 4–6 mm long); the corolla tube dilates more gradually in P. sylvestris and the corolla tube is ± equal in length to the anterior lip, whereas in P. alpinus the tube is usually shorter than the anterior lip.