Vitex congolensis var. thomasii (De Wild.) Meerts, 2018

Meerts, Pierre, 2018, Synopsis of the genus Vitex (Lamiaceae) in the Democratic Republic of the Congo, Plant Ecology and Evolution 151 (3), pp. 380-392 : 384

4b. Vitex congolensis var. thomasii (De Wild.) Meerts , comb. nov.

Vitex thomasii De Wild ., Contribution à la Flore du Katanga, Supplément 2: 106. 1929 ( De Wildeman 1929b); Delevoy (1929: 185); Moldenke (1958a: 148); Lebrun & Stork (1997: 526).

– Type: D.R. Congo, Kalonda, 20 Aug. 1923, Thomas 1324 (holo-: BR barcode BR 0000008906267) .

Vitex thomasii f. kasaiensis De Wild. ( De Wildeman 1929b: 108); Moldenke (1958a: 149).

– Type: D.R. Congo, Kasaï, Bena-Dibele , Luja 259 (holo-: BR barcode BR 0000013602093) .

Vitex buchneri Gürke ( Gürke 1893: 166) ; Baker (1900: 331); De Wildeman (1912b: 280); Pieper (1928: 58); Lebrun & Stork (1997: 524).

– Type: Angola, Kassambo, Büchner 574 (holo-: B †), synon. nov .

Differs from the type variety by the large foliaceous elliptic lower bracts.

Distribution – Subendemic to D.R. Congo, restricted to the southern margin of the distribution range of V. congolensis , i.e. Kasaï and Katanga, very locally extending to N Angola.

Note – Vitex congolensis is a Guineo-Congolian linking species extremely variable as to density, length and intensity of the fulvous color of the indumentum. Variation of indumentum is continuous and cannot be translated into infraspecific units. Vitex thomasii De Wild. is a variant showing a very unusual character, i.e. foliaceous bracts at the lower inflorescence nodes, up to 30 × 8 mm. This is not a teratological condition, because several gatherings from distant localities exhibit such bracts. This variant deserves taxonomic recognition at varietal rank. The type specimen of V. buchneri has not been found. However, the protologue clearly indicates that this taxon belongs here (“…die Bracteen der Nebenachsen erster Ordnung lanzettlich in den Stiel verschmälert, mit dem Stiel bis 3 cm lang…”) ( Gürke 1893).