From the Greek oxys — sharp, petalon — petal, referring to the shape of the corolla lobes.

Annual to perennial herbs, with white latex. Leaves herbaceous; mucilage glands present. Corolla bell- to salver-shaped; tube cylindrical; lobes free at tips, valvate. Annular, corolline and staminal coronas absent; interstaminal corona of 5 lobes that are formed, but not fused, into a tube surrounding the staminal column. Follicles tapered at each end; seeds with hair tufts at one end.

Seed or root divisions.

Blue to purple flowers.

Over 100 species in C and S America (1 species naturalised in Australia).

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.