Clerodendrum buchneri Gürke (1893: 172)

Meerts, Pierre, 2023, The genus Clerodendrum (Lamiaceae) in the flora of Central Africa (D. R. Congo, Rwanda, Burundi), Phytotaxa 594 (1), pp. 1-42 : 8

4. Clerodendrum buchneri Gürke (1893: 172) ; Durand & Schinz (1896: 222); Baker (1900: 305); Durand & Durand (1909: 438); Thomas (1936: 64); White (1962: 367); Huber (1963: 442); Moldenke (1985d: 300); Verdcourt (1992: 102); Lebrun & Stork (1997: 510); Fernandes (2005: 101); Vollesen & Merrett (2020: 863).

Type:— ANGOLA. Malange , Gossweiler 1050 (neotype designated here: K001008526) .

= Clerodendrum strictum Baker ( Baker 1900: 305) . Type :— ANGOLA. Pungo Andongo, January 1957, Welwitsch 5685 (holotype: K000192918, iso-: BM000798651 , G00366331, P00442379 ).

= Clerodendrum hockii De Wild. ( De Wildeman 1911a: 266) . Type:—D.R. CONGO. Haut-Katanga, Vallée de la Luembe, Février 1910, Hock s. n. (holotype: BR0000008929280 & BR0000008929617).

= Clerodendrum humile Chiov. ( Chiovenda 1922: 117) ; Thomas (1936: 64). Type:—D.R. CONGO. Haut-Katanga, Plateau des Bianos, October 1919, Bovone s. n. (holotype: ubi?).

A geofrutex with a thick horizontal rhizome, up to (10–) 15–100 cm high, with annual shoots. Stem erect, mostly simple, tardily lignified at base, terete to slightly angled, shortly hispid, internodes 1.5–4 cm, 7–12 nodes; persistent petiole bases obsolete to ca. 2 mm. Leaves increasing in size from base to top, petiole ca. 0.5–1(–3) cm; lamina obovate to elliptic-obovate, 4.5–11 × (1.5–) 2–5.5 cm, base obtuse, apex obtuse-rounded to abruptly acuminate, more rarely acute, margin entire, rarely undulate-crenate distally, upper surface shortly pubescent, roughish, lower surface shortly pubescent on veins; 3–4(–5) veins on either side, diverging at an acute angle, the lowermost pair from the base, impressed, prominent on lower surface. Inflorescence subsessile, capitate, 30(–40) mm diam. (corollas excluded), rarely ovoid (up to 50(–100) × 30 mm); bracts foliaceous, up to 18 mm long, branches short (<5 mm). Flower: pedicel 3–5 mm, hispid; calyx 16–21 mm, tube obconical, 3–5 mm long, lobes ovate, acuminate, 5–7(–8) mm long, pale green to purplish, reticulum prominulent, ciliate (cilia pallid, up to 1.5 mm); corolla: tube 5–6.5(–7.5) cm, greenish, with glandular hairs 0.5–1 mm, lobes ca. 10 × 6 mm, cream to pale yellow, stamens exserted 20–25 mm, anther ca. 2.5 mm long. Fruit: mericarps obovoid, ca. 13 × 8 mm.

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

Distribution elsewhere:— Angola, Botswana, Tanzania, Zambia, Zimbabwe.

Habitat:—Savannah, dry woodland, fallow field, also in degraded sites; 800– 2200 m.

Selection of representative specimens:— D.R. CONGO. Kasaï: Panzi, 6 February 1952, Callens 3107 (BR!); Feshi , Kwango , 13 March 1956, Devred 2903 (BR!). Lacs Edouard & Kivu: Tanganyika Lake , 10 July 1908, Kässner 5066a (BR!). Haut-Katanga : Baya , 16 May 2006, Faucon & Meerts 74 (BR!); Mont Mukwen , 21 March 1986, Lumbu Simbi 11 (BR!, WAG) ; Lubumbashi , station agricole de Keyberg, March 1937, Quarré 4838 (BR!); Route Pweto-Baudouinville, env. Kisabi, 1050 m, 22 April 1926, Robyns 2069 (BR!); Route Kasumbalesa, 77 km from Lubumbashi, 29 November 1981, Schaijes 1198 (BR!); Biano, 34 km NNW of Tenke, 19 December 1982, Schaijes 1671 (BR!); Biano, à 22 km de Tenke, 30 January 1984, Schaijes 2214 (BR!, with photo!); Marungu, Kasigi, 2200 m, 12 June 1939, Vanden Brande 216 (BR!). — BURUNDI: Rwanda-Burundi : Mugera (territ. Ruyigi), 28 October 1966, Lewalle 1164 (BR!, MO) ; Kininya Mosso, 28 June 1952, Michel 3086 (BR!); Ruyigi, Kigamba , 1 April 1977, Reekmans 5922 (BR!, FHI, WAG) .

Notes:—1. The flowers are occasionally parasitized (fungus?) with corolla tube dilated up to 1 cm thick (e.g. Hock s. n.).

2. C. humile Chiov. is based on a specimen at the lowermost end of size range (calyx ca. 10 mm long, with lobes ca. 3 mm broad), without taxonomic value. The type specimen could not be located.

3. A specimen from Burundi (Reekmans 3094) is unusual in being a shrub (collecting notes: ́shrub, 2 m high») and in having leaf upper surface more densely pubescent; it could represent C. robustum Klotzsch , an East African species; however, it lacks corollas, and more materials are needed to confirm the presence of C. robustum in Burundi.

Neotypification of Clerodendrum buchneri Gürke. Büchner 572 was designated as the lectotype by Thomas (1936), but it has most likely been destroyed and no duplicate was found. The two other syntypes have not been found either (Mechow 429, Mechow 557a). We designate Gossweiler 1050 as the neotype, i.e. a specimen collected in N Angola, in the same region as Büchner 572, and which was cited by Thomas (1936).