Coleus bojeri Benth.

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 bojeri Benth. , Labiat. Gen. Spec.: 52. 1832.

Figs 1 A, B , 2 B

=? Coleus dewevrei Briq. , Bull. Soc. Roy. Bot. Belgique 37: 71. 1899. Type: DR. Congo, s. l., s. d. (see note), A. Dewèvre 1092 A (holotype BR [ BR 0000006262211 ], [ BR 0000006262525 ]).

Type.

Madagascar, Emirna, Betani-Mena, W. Bojer s. n. (lectotype P [P 00541359], designated by Hedge et al. (1998); isolectotype W [ W 0002279]).

Description.

Annual herb, 0.3–0.9 (– 1.2) m high, more or less aromatic; rootstock fibrose, without tubers. Stem erect or, rarely, ascending, quadrangular, branched, indumentum mostly of retrorse and patent eglandular hairs, in the inflorescence only of retrorse, appressed hairs, without glandular hairs or long patent hairs. Leaves opposite, spreading, petiolate, occasionally with small leaves in the axils; petiole (0.5 –) 1.0–4.0 cm long, ciliate, more or less flat and narrowly winged in the upper half; blade ovate-triangular to narrowly ovate, 1.5–4.5 (– 7.5) × 1.0–4.0 (– 6.2) cm, base broadly cuneate, then shortly attenuate into the petiole, rarely subcordate, apex rounded to obtuse or subacute, ca. 4–5 pairs of secondary veins, occasionally impressed on upper surface, sparsely pilose to shortly pubescent on the upper surface, pubescent on veins on the lower surface (either spreading pilose or with antrorse appressed hairs), margin crenate or rarely undulate and subentire. Inflorescence terminal, lax, (4 –) 12–42 × 1.2–2.5 cm in fruit, with 9–30 verticils spaced 5–25 (– 30) mm, cymes sessile, ascending, ca. (7 –) 9–25 - flowered, cincinni ca. 1–2 mm long at anthesis, elongating in fruit to 1–7 (– 12) mm, pedicels 1–3 (– 4) mm long, inserted eccentrically in front of calyx upper lobe, curved at tip, bracts ovate, 2–4 mm long, acute to acuminate, cucullate, forming an inconspicuous coma, early caducous. Flower: calyx shortly pubescent, with red sessile glands, 1.5 mm long at anthesis, 3–5 mm long in fruit, tube shortly cylindrical, truncate, slightly constricted at throat, upper lip often purplish tinged, ovate to obovate, curved upwards, obtuse to rounded, occasionally subacute, apiculate, 1.5–2 mm long, lateral lobes of lower lip truncate, ca. 1 mm, middle lobes of lower lip fused in a linear bidentate lobe 2–3 mm long. Corolla blue or violet, rarely white, with red sessile glands, 8–9 mm long, tube 3–4 mm, sigmoid, lower lip 4–6 mm long, 1.5–2.5 mm deep, enclosing stamens and style, stamens fused, style bifid. Nutlets globose, brown, red speckled, 0.8–1 mm.

Distribution.

Senegal, Mali, Sierra Leone, Ivory Coast, Ghana, Togo, Benin, Nigeria, Cameroon, Congo, Gabon, Sudan, South Sudan, Ethiopia, Uganda, Kenya, Tanzania, Mozambique, Malawi, Zambia, Zimbabwe, Angola, Madagascar.

Habitat and ecology.

Rainforest, dry woodland, savannah, fallow fields, rock outcrops, occasionally an epiphyte, 370–1900 m elev.

Additional specimens.

DR. Congo, Bas-Congo, 15 km N Kisantu, 5 Apr 1944, R. Germain 2043 (BR); Kasaï, Bilala, 22 Feb 1937, J. Gillardin 210 (BR); Route Kindu-Katako Kombe (km 64), 14 Apr 1959, P. Bamps 475 (BR); Bas-Katanga, Lofu, 26 Mar 1947, L. Van Meel 1283 (BR); Forestier Central, Namoya, near Shapandi, 15 Apr 2008, B. Bytebier & W. R. Q. Luke 2965 (BR); Secteur Bangengele, Lomami, 3.9 km NNE Katopa, 6 Apr 2015, R. Gereau et al. 7407 (BR, MO); Ubangi-Uele, Dendu, Sep 1921, J. Claessens 1708 (BR); Bambesa, 31 Oct 1956, P. Gérard 2392 (BR); Lac Albert, Nioka, 1934, F. Jurion in J. Claessens 215 (BR); Kasengi, Oct 1931, J. Lebrun 4100 (BR); Lacs Edouard et Kivu, Riv. Kahekavitiri, affl. de rive droite de la Mukandwe, près de Mutsora, 12 Jun 1954, G. F. de Witte 10529 (BR); Ruwenzori, entre Mutwanga et le gîte Kalonge, 28 Dec 1977, J. Lejoly 2233 (BR); Haut-Katanga, Env. Elisabethville [Lubumbashi], 1923, S. de Giorgi s. n. (BR); Kumanua, 4 Feb 1976, F. Malaisse 8963 (BR); Marungu, ravin de Kafwampa, May 1945, P. J. J. Vanden Brande 279 (BR).

Rwanda, Lac Kivu, route Nyamasheke-Kibuye, km 19, 29 Mar 1972, G. Bouxin & M. Radoux 1526 ( BR).

Burundi, Mosso, 7 Jun 1952, G. Michel 2584 ( BR); Bururi, Resha, 26 May 1981, M. Reekmans 10379 ( BR, MO, US).

Senegal, Massif de Kita, 7 Oct 1943, P. Jaeger 32 ( K).

Mali, Kayes Region, Kenieba Cercle, Falea Rockgate Mine, 24 Oct 2012, W. R. Q. Luke & Sanogo 15850 ( EA, K, IER).

Sierra Leone, West of Kambia N. P. 3 Nov 1963, J. K. Morton SL 74 ( SL, GC, FHI, K, WAG).

Ivory Coast, Northern part of Bouna Reserve, Téhini, about 40 km E of Ouangofétini, 24 Aug 1963, W. J. J. O. de Wilde 752 a ( K, WAG).

Ghana, Gambaga Scarp, grown from seed at Legon, 3 Apr 1961, J. K. Morton s. n. ( GC, K).

Togo, 15 km S of Dapaon, 10 ° 44 ' N, 0 ° 12 ' E, 11 Oct 1977, Ern et al. 1546 ( B, K). Benin, Borgou, Tchaourou, Ouari-Maro, 9 ° 00 ' N, 2 ° 15 ' E, 24 Aug 1999, B. Sinsin 2900 ( K, WAG). Nigeria, NE State, Mambilla Plateau, 27 May 1972, J. D. Chapman 2835 ( FHI, K). Cameroon, Balowa, Balikambat, 13 Sep 1960, S. Gillett 2 ( K).

Congo (Brazzaville), Lekoumou Préfecture, Zanaga Project, near Yakatopema / MPD Congo SA camp. 2 ° 46 ' 40 " S, 13 ° 35 ' 52 " E, 4 Oct 2009, M. Cheek 15095 ( IEC, K).

Gabon, Haut-Ogooué, Plateaux Batéké National Park, Mpassa River Drainage, Harunga forest, 2 ° 12 ' 36 " S, 14 ° 01 ' 56 " E, 2 Mar 2003, G. Walters & R. Niangadouma 1194 ( K, MO).

Sudan, Jebel Marra, Colol, 23 May, 1968, A. A. Kamil 1088 ( K).

South Sudan [Bongo Land], Oct 1877, G. Schweinfurth 2490 ( K; type of Plectranthus bongensis Baker ). Ethiopia, Joje, 10 km S of middle Abay Bridge, 10 ° 12.70 ' N, 36 ° 59.29 ' E, 11 Oct 2010, I. Friis, W. Abebe, E. Getachew 13412 ( AAU, K).

Uganda, Ajai Wildlife Reserve, 10 Dec 2001, J. Kalema JK 1094, ( K).

Kenya, 4 km from Webuye on road to Kitale, 0 ° 38 ' N, 34 ° 46 ' E, 10 Oct 1981, M. G. Gilbert & M. Tadessa 6583 ( EA, K).

Tanzania, Kagera, Bukoba Rural District, Minziro Forest Reserve, Nyokabanga, kaiyamba Hill, 01 ° 02 ' 20 " S, 31 ° 32 ' 04 " E, 18 May 2001, L. Festo, W, Bayona, & W. Wibard 1485 ( K, MO).

Mozambique, Sussundenga Distr., E slopes of Chimanimani Mts, West of Dombe, Mevumosi River Valley, streamside, 27 Apr 1974, G. Pope & T. Müller 1330 ( K).

Malawi, Rumphi Distr., Rukuru Bridge, junction to Rumphi to Livingstonia, 29 Apr 1971, Pawek 4756 ( K, MAL).

Zambia, Chingola, 5 Aug 1955, D. B. Fanshawe 2411 ( K, NDO).

Zimbabwe, Mrewa, Shawanae River, 23 Apr 1956, H. Wild 4806 ( K, SRGH).

Angola, Lunda Norte, near Kasamba Village ca. 59 km NNW of Capaia on road to Carumbo, 7 ° 50 ' 15 " S, 20 ° 01 ' 46 " E, 4 Apr 2013 D. J. Goyder & I. Darbyshire 7209 ( K).

Madagascar, N of Ankazobe, Mar 1930, M. R. Decary 7364 ( K, P).

Notes.

1. C. bojeri is defined here in a narrower sense compared to recent floras ( Paton et al. 2009, 2013, 2022), excluding C. chevalieri , C. collinus and C. heterotrichus . It is restricted to specimens without persistent bracts (or rarely persistent at the two lowermost nodes), with short cincinni and stem indumentum mostly of retrorse hairs, without long patent hairs in the inflorescence.

2. C. bojeri is a polymorphic taxon possibly still in need of further splitting. One of the most distinctive morphs was named Coleus platostomoides Robyns and Lebrun (1928) 362. (Type: W. Robyns 2482 (holotype BR; isotype P), DR. Congo, Lac Kivu, baie de Sake, plaine de lave de Kateruzi, 10 Jun 1926). It differs in the shoot much branched from base, the longer cincinni (rachis up to 12 mm long in fruit) with closely spaced pedicels (ca. 15 flowers / cincinni) distichously arranged in a fish-bone pattern at fruiting; it has a distinctive ecogeographic distribution, restricted to volcanic lava in Kivu (e. g. Parc National Albert [Rumoka], 21 Apr 1945, R. Germain 3785 & 3786 ( BR, L); Territ. Beni, Kusolu, Oct 1938, P. Gille 129 ( BR); Beni, 31 Jul 1914, J. Bequaert 5140 ( BR); Parc National Albert [Virunga], Kahodju, Aug 1937, J. Lebrun 6925 ( BR, P); Entre le volcan Rumoka et la baie de Sake, Aug 1937, J. Louis 4861 ( BR, P); Plaine de lave près de Ngoma [Goma], Apr-May 1929, H. Humbert 7901 (P). However, specimens showing one or several of these traits are occasionally found elsewhere (e. g. Kasaï, Territ. Dibaya, riv. Mwanzangoma, 9 Jan 1957, L. Liben 2220 ( BR); Uganda, A. D. Poulsen, G. Eilu & D. Hafashimana 1260 [ C, K, MHU]) and intermediates with typical C. bojeri are not rare in Kivu. Evidence from molecular markers is needed to further resolve the taxonomy of this difficult group.

3. The specimen A. Léonard 2040 (Mikwati, territ. Walikale, 16 Dec 1958 [BR]), a subglabrous plant with very small (ca. 10 × 5 mm), acute leaves and a long calyx (6 mm in fruit), is probably a different taxon, but more materials are needed.

4. The specimen Yona Mleci 19 ( BRLU), collected on termite mounds in miombo woodland near Lubumbashi, has roots with numerous clavate tubers; it approaches Coleus botryosus , differing in the caducous bracts; it could be a different taxon, but more materials are needed.

5. In Burundi, a few specimens are more or less intermediate between C. bojeri and C. homblei (e. g. Bururi, Lac Nyanza, route de Makamba, 19 Mar 1967, J. Lewalle 1698 [ BR]) and between C. bojeri and C. collinus (e. g. Munvugo, 3 km N Nyanza, 16 Apr 1978, M. Reekmans 6920 ( BR, LG).

6. The type specimen of Coleus dewevrei De Wild. is possibly a perennial plant, more or less intermediate between C. bojeri and C. welwitschii or C. brazzavillensis .

7. See observations under C. homblei .

Figures

Figure 1. Coleus bojeri complex, details of inflorescence architecture and stem pubescence in four species A, B Coleus bojeri Benth. (T. Sperry 179) C, D Coleus chevalieri Briq. (P. Gérard 4297) E, F Coleus collinus Robyns & Lebrun (J. Lebrun 9041) G, H Coleus heterotrichus Briq. (M. Micha 300). Drawn by Hilde Orye. Scale bars: 1 mm (B, D, F, H); 2 mm (A, C, E, G).

Figure 2. Coleus bojeri complex, leaf shape in four species A Coleus collinus (J. Lewalle 1936) B Coleus bojeri (T. Sperry 179) C Coleus chevalieri (P. Gérard 4297) D Coleus heterotrichus (P. Quarré 3159). Drawn by Hilde Orye. Scale bar: 1 cm.