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A shrub or small tree to about 35 ft high in the wild. Leaves sessile, closely set, narrow-elliptic or narrow-oblong, up to 2 in. or slightly more long and about 1⁄2 in. wide, acute, three- or five-veined from the base with a variable number of cross veins. Flowers solitary, terminating lateral shoots, stellate in form, 15⁄8 to sometimes 3 in. wide. Sepals variable in shape, soon recurved, glandular on the back and usually at the edge. Petals golden yellow or orange-yellow, flushed red on the outside, persistent. Stamens about half as long as the petals, united for most of their length. Sect. Campylosporus.
A native of Africa from Ethiopia to the Transvaal, and of south-west Arabia, ascending to nearly 13,000 ft in the mountains of east Africa, where the slightly differentiated subsp. keniense (Schweinfurth) N. Robson also occurs, with intermediates between it and the typical subspecies. This species has been a very rare inhabitant of British gardens for at least half a century, often under the name ‘H. kenyense’, and although damaged in severe winters, has flowered occasionally. The late Norman Hadden had it in his garden at Underway near Porlock, Somerset, and Dr Robson tells us that there are flowering specimens from him in the British Museum Herbarium dated 1935 and 1959. This introduction is believed to have come from Mount Kilimanjaro and the Underway plant indeed matches specimens from this mountain, being intermediate between subsp. revolutum and subsp. keniense.
H. revolutum also grows and has flowered at Malahide Castle near Dublin, where it was planted by the late Milo, Lord Talbot de Malahide. It is of unknown provenance and belongs to subsp. revolutum. A plant at Wakehurst Place in Sussex was raised by Mrs Robson from seeds collected on Zomba mountain in Malawi by Mrs Isobyl La Croix around 1977 and is the only one of this batch to have survived. H. revolutum is also known to have flowered in the garden of Miss Davenport-Jones in Kent.