Coleus tenuicaulis Hook. f.

Meerts, Pierre J. & Paton, Alan J., 2024, The genus Coleus (Lamiaceae) in Central Africa (Democratic Republic of the Congo, Rwanda, Burundi), with the description of 15 new species, PhytoKeys 246, pp. 71-178 : 71-178

Coleus tenuicaulis Hook. f. , J. Proc. Linn. Soc., Bot. 7: 211. 1864.

Type.

Cameroon, Mt Cameroon, Dec 1862, G. Mann 1939 (holotype K [ K 000431854 ]).

Description.

Perennial herb 0.3–0.65 (– 1.50) m high, rootstock weakly rhizomatous. Stem erect, quadrangular, variously pubescent, often with short retrorse hairs, occasionally with patent eglandular hairs, short glandular hairs and papillae, densely glandular pubescent in the inflorescence, erect, branched. Leaves opposite, patent, often with young leaves in the axils, petiolate, upper ones subsessile; blade ovate-triangular, (narrowly ovate out of Central Africa), 1.5–6.5 (– 7.5) × 1.0–5.0 (– 6.5) cm, base broadly rounded, truncate or subcordate, more rarely cuneate, shortly attenuate in the petiole, apex acute, margin serrate, upper surface densely pubescent (very short papilliform hairs), lower surface pubescent on veins, ca. 4–5 pairs of secondary veins; petiole 1.0–3.5 (– 4.0) cm long, with very short retrorse hairs and often also long patent hairs. Inflorescence terminal, lax, 4–18 cm long, with 5–14 verticils spaced 7–30 mm, bracts narrowly ovate, ca. 3 mm long, acuminate, caducous or rarely persistent, cymes ascending, ca. 9–25 - flowered, pedunculate, peduncle 1–15 mm long, with two opposite cincinni ca. 5–50 mm long, densely papillate, pedicel 1–4 mm long, widely spaced, inserted eccentrically. Flower: calyx 2 mm long at anthesis, densely papillate and with red sessile glands, ca. 5–6 mm long in fruit, tube slightly curved, slightly constricted at throat, upper lip ovate, ca. 2–3 mm long, markedly curved, subacute, slightly decurrent, lobes of lower lip narrowly triangular, sharply acute, the lateral ones 2 mm long, the middle ones 3 mm long. Corolla pale blue to violet, with pale sessile glands, ca. 10–15 mm long, tube strongly sigmoid, ca. 4 mm long, lower lip ca. 6–8 mm long, 3–4 mm deep, enclosing stamens; filaments fused, anther ca. 0.8 mm, style entire. Nucule pale brown, round, compressed, ca. 1 mm diam., dull, smooth.

Distribution.

W Tropical Africa to Cameroon, SW Tanzania to S Tropical Africa.

Habitat and ecology.

Dembo, wooded savannah, most often on moist soil; 800–1815 m elev.

Additional specimens.

DR. Congo, Kasaï, Kwango, Twana, 12 Sep 1953, H. Callens 4223 ( BR); Kwango, Kibunda, 27 Apr 1953, H. Callens 4001 ( BR); 50 km W of Kimvula, 12 Apr 1948, P. Duvigneaud 715 ( BRLU); Haut-Katanga, Upemba, riv. Lusinga, 21 Oct 1948, L. van Meel in de Witte 4566 ( BR); Upemba, 29 Jul 1949, L. van Meel in G. F. de Witte 7128 ( BR); Kasombo, 22 Jan 1957, E. Detilleux 457 ( BR); Kundelungu, 6 km NNW poste de Katshupa, rivière Luanza, 29 Jul 1966, F. Malaisse 4213 b ( BR, LSHI); Kundelungu, rivière Kabunda, 28 Mar 1971, S. Lisowski 23387 ( POZG); Dembo de la Katuba, Feb 1934, P. Quarré 3833 ( BR).

Notes.

1. New species record for DR. Congo.

2. P. Quarré 3833 (BR) and Lisowski, Malaisse & Symoens 4930 ( POZG) are unusual in having lower leaf surface and stem tomentose.