Coleus brazzavillensis A. Chev.

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 brazzavillensis A. Chev. , Veg. Ut. Afr. Trop. Franç. 1: 124. 1905.

Type.

Republic Of Congo (Brazzaville), 1904, A. Chevalier 11154 (holotype P [P 00450785]).

Description.

Perennial herb 0.30–0.75 m high, not reported to be aromatic, with a thin creeping rhizome, tubers not collected in DR. Congo (present in Rep. Congo). Stem ascending, rooting at lower nodes, simple or more rarely sparingly branched, quadrangular, more or less villous, with long patent flexuous hairs up to 2 mm long, these occasionally sparse or restricted to nodes and short retrorse hairs, in the inflorescence with shorter patent or antrorse hairs (0.5 mm), intermingled with sparse much longer hairs and also with red sessile glands. Leaves opposite, petiolate, ascending to spreading, occasionally with smaller leaves in the axils; petiole 0.5–2.5 cm long, with flexuous patent hairs 2–3 mm long, these sometimes sparse, and short retrorse hairs, narrowly winged in upper half, blade ovate to ovate-elliptic, 1.5–8 × 1–3 cm, apex obtuse to acute, base cuneate and shortly attenuate, ca. 5 pairs of secondary veins, margin crenate, narrowly recurved, both surfaces pubescent with long erect to appressed hairs, especially on veins beneath and with red sessile glands beneath. Inflorescence lax, (4 –) 9–18 cm long, with 7–15 verticils spaced (5 –) 10–25 (– 45) mm, bracts ovate, ca. 5 × 3 mm, acuminate, forming an apical coma, deciduous, except often at 1–2 lowermost nodes where they are somewhat foliaceous and crenate; cymes sessile to very shortly pedunculate (1 mm), ascending, ca. 13 - flowered, cincinni up to 6 mm long in fruit, pedicels 1–4 mm, inserted eccentrically behind calyx upper lobe. Flower: calyx shortly pubescent and with red sessile glands, ca. 1.5 mm long in flower, up to 4.5 mm long in fruit, tube shortly cylindrical, constricted at throat, truncate, upper lobe ovate, recurved, subacute, purplish tinged, ciliolate, lateral lobes truncate, middle lobes of lower lip fused in a linear lip ca. 3 mm long, with two subulate points; corolla ca. 9–14 mm long, tube ca. 4 mm long, strongly sigmoid, lower lip ca. 5–7 mm long, 2.5–3 mm deep, cucullate, upper lip 2 mm long, with a broad gap between the two lips. Nutlets pale brown, globose, ca. 0.9 mm diam., smooth.

Distribution.

Republic of Congo (Brazzaville), DR. Congo.

Habitat and ecology.

Marshland, wet savannah, grassy clearings, Sphagnum bogs, dry woodlands; 300–750 m elev.

Additional specimens.

DR. Congo, Bas-Congo, Léopoldville [Kinshasa], 15 Apr 1915, J. Bequaert 7341 (BR); Boko Mfumu Disu, 15 Nov 1948, H. Callens 1911 (BR); Madimba, 2 Apr 1948, P. Duvigneaud 609 Ca ( BRLU); Entre Ngidinga et Kimvula, 12 Apr 1948, P. Duvigneaud 703 C ( BRLU); Boko sur chemin de fer, Apr 1932, H. Vanderyst 29736, 29747, 29751 (BR); Kasaï, Kwango, Mela, H. Callens 1677 (BR); Panzi, 8 Feb 1950, H. Callens 2185 (BR); Region of Luebo, s. d., L. Achten 415 a & b; Forestier Central, Entre Bokatola et Bikoro, Lac Léopold II [Lac Mai Ndombe], Sep 1930, J. Lebrun 1445 (BR).

Notes.

1. New species record for DR. Congo.

2. C. brazzavillensis was hitherto a poorly-known species. It is superficially similar to C. bojeri , differing in being perennial. C. brazzavillensis is closely related to and, arguably, only a variety of C. welwitschii , differing in the much more slender rhizome, longer hairs on shoot and petiole, shorter cincinni, persistent bracts at lowermost verticils and its occurring in moist habitats; blade length / width ratio also tends to be greater than in C. welwitschii . Its range is restricted to W DR. Congo and Congo (Brazzaville).

3. H. Callens 2185 (BR) has the indumentum of the stem much sparser than usual. J. Lebrun 1445 (BR) is unusual in having persistent bracts at all verticils.