Epiphytic or terrestrial shrub or small tree, up to 2 m, rarely 5 m, young stems green with fine stellate scales but quickly becoming glabrescent or (var. cladotrichum Sleumer) with fine simple hairs. Leaves 10–30 × 3–9 cm, narrowly elliptic or elliptic, the apex acute to obtuse, often shortly acuminate, the margin entire and flat, the base broadly to narrowly tapering; the upper surface at first with a fine silvery appressed covering of scales but quickly becoming glabrous, or minutely hairy (var. cladotrichum), often characteristically puckered with hollows between the lateral veins, midrib slightly raised in the lower half, lateral veins 8–12 pairs distinct but not raised; lower surface with the midrib raised for about 2/3 of its length, the laterals hardly raised, scales, lobed discs with small centres, small and widely spaced and with small white hairs, especially on the veins in var. cladotrichum. Flowers 3–12 per umbel, erect to horizontal; calyx a low scaly ring; corolla pale yellow through orange to red, sometimes strikingly bicoloured with a yellow throat and orange lobes, funnel-shaped, 4–6 × 4–5 cm, glabrous outside, reported as having a delicate lemon-like fragrance but usually scentless; stamens 10, irregular or somewhat placed into two lateral groups; ovary with simple hairs and scales (glabrous in subsp. moultonii \[Ridl.\]Argent), style glabrous. Royal Horticultural Society (1997)
Distribution Indonesia Borneo (widespread), W & N Sumatra
Habitat s.l. to 1,800 m
RHS Hardiness Rating H1c
Awards FCC 1869 (J. Veitch, Chelsea, London); flowers clear yellow. FCC 1970 (Mr & Mrs E.F. Allen, Felcourt, Copdock, Suffolk) to a clone 'Mandarin'; flowers Red Group 40C, fading to 40D, throat bright yellow (between Yellow-Orange Group 18A and 17D).
Conservation status Least concern (LC)
This species is common in Borneo and has occasionally been found in Sumatra, it is very variable and still poorly understood as a species despite having been cultivated in various forms for a long time. The bicoloured forms from Mt Kinabalu produce exceptional flowers and it was one of these that was registered as ‘Mandarin’. This species is of easy cultivation and it has the advantage that the flowers are most commonly produced in the depths of winter.
With narrower leaves rarely more than 3cm wide.
Awards FCC 1972 (Mr and Mrs E.F Allen, Felcourt, Copdock, Suffolk) to a clone ‘Raja’; flowers Yellow Group 13A.
Taxonomic note (syn. R. brookeanum var. gracile [Low ex Lindl.] G. Henslow)