Clerodendrum thomsoniae Balfour f. (1862: 233)

Meerts, Pierre, 2023, The genus Clerodendrum (Lamiaceae) in the flora of Central Africa (D. R. Congo, Rwanda, Burundi), Phytotaxa 594 (1), pp. 1-42 : 32-33

24. Clerodendrum thomsoniae Balfour f. (1862: 233) ; Hooker (1862: pl. 5513); Baker (1900: 303); Thomas (1936: 60); Deuse (1960: 65); Huber (1963: 442, fig. 307); Verdcourt (1992: 87); Lebrun & Stork (1997: 513); Fernandes (2005: 94); Lisowski (2009: 364); Lejoly et al. (2010: 295).

Type:— NIGERIA. Plant cultivated at Edinburgh Botanic Garden , from a plant collected at Old Calabar by Thomson (holotype: E00193470, iso-: E00193471) .

Liana up to 9 m. Stem papillate to puberulent, obtusely tetragonal, persistent petiole base ca. 1 mm long. Leaves: petiole 0.5–3.5 cm, papillate to puberulent; lamina ovate, 4.5–18 × 2–8 cm, base rounded to subcordate, apex acute to acuminate, membranous, 2–4 veins on either side, upper surface subglabrous to scabridulous, lower surface subglabrous, margin entire to slightly crenate. Inflorescence in axillary cymes, those of the uppermost 2–3 nodes grouped in a terminal corymb 11–15 × 14–20 cm; cymes 5–9 × 4–8.5 cm very lax, 7–17 flowered, peduncle 2.5–5.5 cm, basal bracts narrowly elliptic, attenuate at base, ca. 22 × 8 mm. Flower: bracteoles linear, 3 mm long, pedicel 3–13 mm, puberulent; calyx 16–22(–30) mm, tube obconical 2–3 mm long, puberulent, abruptly dilated into a pentagonal limb, white at first, turning yellowish to rose, lobes ovate-triangular, 14–20 × 7–9 mm, acute, puberulent, shortly ciliolate; corolla red, tube 20–25 mm, lobes 6–10 mm long, with short glandular hairs; stamens exserted 20–25 mm. Fruit not observed.

Distribution in Central Africa:—D.R. Congo.

Distribution elsewhere:— Cameroon, Gambia, Ghana, Gulf of Guinea Is., Nigeria, Senegal, Sierra Leone. Introduced to tropical Asia and America.

Habitat:—Apparently only a garden escape.

Selection of representative specimens:— D.R. CONGO. Bas-Congo: “région de l’Equateur”, au Jardin d’Yudu (?), 27 June 1925, Gillet in Robyns 13 (BR!) . Haut-Katanga: Lubumbashi, Pépinières P. Van Kerkhoven, July 1937, Schrooten in Salésiens 197 (BR!) .

Note:—1. It is unclear if C. thomsoniae is native in Central Africa; the few specimens in collections appear to be cultivated plants, or garden escapes.

2. The specimen Bytebier & Luke 2763 (BR!) is closely related to C. thomsoniae ; however it has corolla cream-coloured with only one red lobe, and the calyx is densely lepidote. It could represent a different taxon.