Stems erect, or shortly decumbent, 5-angled. Corolla deeply bell-shaped, 20-35 mm wide, inside of lobes and tube dark brown or brown-purple; annular corona absent; densely papillate.

Kenya

 

H. insigniflora Maas from S Africa has stems erect, 4(rarely 5)-angled. Corolla flattened, bell-shaped, 25-35 mm wide, inside of lobes cream; annular corona shiny, reddish; smooth. H. schneideriana Berger from Tanzania has stems erect, 7(rarely 6)- angled. Corolla flattened, bell-shaped, 25-30 mm wide, inside of lobes and tube dark brown; annular corona absent; papillate. H. volkartii Werderm. & Peitsch var. repens (Lavranos) Lavranos from Angola, Mozambique, Namibia and Zimbabwe has stems erect or shortly decumbent, 5-angled. Corolla flattened, bell-shaped, 20-30 mm wide, inside of lobes and tube cream, with concentric lines of dull crimson; shiny annular corona absent; densely papillate. H. zebrina N.E. Br. from S Africa and Zimbabwe has stems erect, 5(rarely 6)-angled. Corolla flattened, bell-shaped, 35-50 mm wide, inside of lobes cream to yellow, with transverse stripes of red, red-brown or purple; annular corona present, shiny, reddish to dark purple-brown; smooth.

Source: Forster, P.; Liddle, D.; Liddle, I. (2002). Hoya. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.