Description

Shrub to 1m. Twigs c.4mm in diameter, green, rounded, laxly to sub-densely, pale-brown scaly and minutely, sparsely shortly patently hairy; internodes 2–12cm. Leaves loosely spirally arranged along the stem. Blade 50–100 x 43–60mm, broadly ovate or ovate-elliptic, occasionally broadly elliptic; apex obtuse, rarely rounded and mucronate but without an obvious apical gland; margin entire, flat, with a thin (c.0.5mm), reddish-purple edge; base distinctly cordate, occasionally broadly tapering and then with translucent auricles at the base of the lamina; glabrescent above, laxly and more persistently scaly beneath. Scales stellate, pale-brown, marginal zone appressed to the leaf surface; centres small and impressed. Mid-vein strongly raised above for about ¾ of the length of the leaf, slightly raised beneath or shallowly impressed in the proximal ½; lateral veins 7–10 per side, spreading almost perpendicularly, strongly raised above, the leaf surface deeply sulcate between the veins, disappearing before the margin, reticulation weak or obscure. Petiole 10–23 x 4–5mm, reddish-purple, rounded above, without a groove, sparsely to sub-densely scaly. Flower buds ovoid, 20–35 x 15–22mm, bracts firmly appressed except for a very short point. Outer bracts translucent, truncate to emarginate, almost glabrous, with just a few small scales outside but without any on the margins. Inflorescence a 5–8-flowered open umbel, the flowers held horizontally. Pedicels 34–38 x c.3mm, shortly, white, patent-hairy and with a few papillae towards the distal end but without scales. Calyx green, glabrous or with a few low, irregular papillae. Corolla 55–65 x 50–60mm, bright golden yellow, often flushed with orange on the tube and around the edges of the lobes, without scent; tube c.30 x 12 x 22mm, funnel-shaped, glabrous outside but densely shortly white, patent-hairy in the proximal ½ inside, conspicuously 5-lobed at the base; lobes 35 x 27mm, spreading almost at a right angle and overlapping to over halfway, glabrous. Stamens irregularly spreading around the mouth of the flower, occasionally in two groups, slightly dimorphic; filaments white, densely white hairy proximally, the hairs thinning distally and becoming glabrous for the uppermost 2⁄3; anthers c.4 x 1mm, arching inwards, tapering towards the base which is distinctly apiculate. Disc purplish-brown, lobed, shortly white hairy on the upper side. Ovary 10 x 5mm, green, sparsely patently white hairy and with a few rounded silvery scales, abruptly tapering distally; style 20 x 1.5mm, glabrous, green, slightly broadened to the pink, circular but 5-lobed stigma. Fruit 20–30 x 8–10mm, green or flushed red, often flecked with white, fusiform. Seeds c.3mm, without tails 0.8mm, the longest tail 1.5mm.

Distribution

Malaysia (Borneo), Sarawak, 4th Division, Mulu National Park, Mt Api.

Altitude

Habitat

Common in the sub-alpine shrubbery of the summit ridge, growing on deep peat which overlies limestone.

Nomenclatural History

Notes

References

Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:261