Euphorbia otjipembana subsp. otjipembana

Bruyns, Peter V., Klak, Cornelia & Hanáček, Pavel, 2020, A review of the Euphorbia schinzii-complex (Euphorbiaceae) in southern Africa, Phytotaxa 436 (3), pp. 201-221 : 209

6a. Euphorbia otjipembana subsp. otjipembana

Euphorbia otjipembana subsp. okakoraensis Swanepoel (2013: 53) . Type:— NAMIBIA. Kaokoveld: North-eastern slopes of Okakora near Okombambi, 930 m, 24 March 2007, Swanepoel 271 (holotype WIND, isotype PRE!).

Discussion: —In plants from around the type locality, the bright green colour of their branches usually makes them easily distinguishable from E. kaokoensis or from subsp. fluvialis , which both occur within 20 km of it. However, away from this locality, the branches are rarely such a bright green and they may even be grey-green (as in plants from further west in the Otjihipa, Bruyns 8041 (BOL) and further east in the Baynes Mtns, Bruyns 8001 (K)). Then it is their relative stoutness (to 45 mm thick) that is distinctive. Of the four spines on each spine-shield, the two below the leaf-rudiments are shorter in subsp. otjipembana than in either E. kaokoensis or subsp. fluvialis . The stipular prickles of subsp. otjipembana are also shorter than in these others.

The cyathia of subsp. otjipembana differ from those of E. kaokoensis and subsp. fluvialis in usually being bright yellow, rather than somewhat pinkish. Their glands are mostly more spreading, rather than nearly erect as in the others. Nevertheless, in the lateral cyathia in some cymes of subsp. otjipembana , the glands may be more erect than in the central cyathium and, in plants from the western side of its distribution (e.g., Okakora, Swanepoel 271 (PRE) and Otjihipa, Bruyns 8041 (BOL)), the cyathia are often suffused with pink and their glands are more erect. Bright yellow cyathia with more spreading glands have occasionally been found in subsp. fluvialis too (e.g., Angola, mountains above Iona, Bruyns 10387 (BOL)), but they are unknown in E. kaokoensis .

Swanepoel (2013) described a further subspecies from slightly west of the type locality of E. otjipembana , which differed by its greyer stems, more pinkish cyathia with more erect glands. However, this is now considered to fall within the variability of subsp. otjipembana . This is especially since plants from even further west than the type of this new subspecies (from Otjihipa, Bruyns 8041 (BOL)) are also considered to belong to subsp. otjipembana .

Additional specimens examined: — NAMIBIA. Otjomborombonga (1712BB), 680 m, Leistner et al. 135 (K, PRE); Leistner et al. 155 (K, PRE). NE slopes of Okakora near Okombambi (1712BB), 930 m, Swanepoel 271 (PRE, WIND). Way to Otjihipa (1712BC), 1200 m, Bruyns 8041 (BOL). 35 km NW of Etengua (1712BD), 1200–1600 m, Bruyns 8019 (BOL). North of Otjipemba (1712BD), Leach & Cannell 15044 (BM, K, etc). Otjipemba (1712BD), Meyer 1309 (M). Baynes Mtns (1713AA), 1500–1600 m, Bruyns 8001 (K).