Benn. & Br., Pl. Jav. Rar. 1838. 86 in text, 88 t.20.
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Shrub or small tree to 7m, erect or more rarely prostrate. Twigs rounded, younger parts red, at first densely covered with stalked round scales, which fall early, the persistent stalks making the twigs rough; internodes 2–6cm. Leaves 4–7 together in pseudowhorls at the upper nodes. Blade 20–60 x 10–20mm, obovate to broadly elliptic; apex distinctly retuse more rarely rounded; margin flat or distinctly recurved, entire; base tapering, dark green and shining above, paler to almost whitish green and dull beneath, laxly to sub-densely scaly on both sides initially, quickly glabrescent above but persistently scaly beneath. Scales disc-like, variable in size, marginal zone narrow and entire, the centre large and thick, distinctly impressed. Mid-vein impressed above, strongly raised beneath; lateral veins 4–7 per side, the lower ones ascending, distal ones irregularly spreading, all slightly impressed above in fully mature leaves, often only faintly visible when fresh, obscure beneath. Petiole 1–5 x 1.5–2mm, thick, grooved above, scaly and becoming rugose, often minutely hairy above. Flower buds to 14 x 9mm, ellipsoid or narrowly ellipsoid, pink, both terminal and lateral, smooth, the bracts fully appressed. Bracts to 13 x 8mm, outer subulate to ovate-acuminate, inner gradually increasing in size and broadly ovate to spathulate, shortly acute, scaly and densely appressed hairy outside, glabrous inside, all densely and long white-ciliate on the margins. Bracteoles to 8mm, linear to filiform, slightly expanded at the apex and hairy in the upper part. Inflorescence a 4–10-flowered open umbel; flowers often semi-erect on opening, becoming half-hanging to hanging. Pedicels 12–20 x c.1mm, densely patently hairy, scaly only near the apex. Calyx c.4mm in diameter, oblique, shortly 5-lobed, densely scaly outside, the lobes c.1mm, long ciliate. Corolla 22–35 x 13–15mm, narrowly funnel-shaped to tubular, red to orange-red; tube 12–28 x 4–6 x 7–8mm, straight, the base slightly dilated in the form of a ring, laxly to densely yellow-scaly and shortly white patent hairy outside, glabrous inside; lobes 4–6 x 3–6mm, erect to half-spreading, broadly elliptic to sub-circular, hairy and scaly outside except near the margins. Stamens alternately slightly dimorphic, exserted to 6–8mm, loosely spreading around the mouth or more tightly clustered on the lower side; filaments linear, widened below, glabrous; anthers c.1.5 x 1mm, broadly oblong, truncate at the top. Disc glabrous. Ovary 3–4 x c.2mm, conical, 5-angular or grooved, densely scaly, not hairy at all; style filiform, scaly at the base only, otherwise glabrous; stigma globose, shortly 5-lobed at the mouth of the flower when it opens, becoming exserted on the lower side of the flower to 8mm. Fruit 10–18 x 5–6mm, erect, oblong-fusiform; valves recurving to about horizontal, the placentae remaining coherent to the central column at first, eventually breaking away at the base and slightly spreading. ** * Rhododendron retusum * var. * trichostylum * ** Leaves 15–25 x 7–14mm. The style laxly patently hairy at the base or in the proximal ½.
Indonesia, Sumatra, Java especially W Java; in C Java known only from Mt Prahu (Dieng) and Mt Merapi; in E Java from Mt Ardjuno. ** * Rhododendron retusum * var. * trichostylum * ** Indonesia, N Sumatra, Atjeh: Goh Lembuh, Putjuk Angasan, Bur ni Tèlong,
Mostly terrestrial in sub-alpine mossy forests or shrubberies, in soil rich in humus and the moss-cushions of old fallen trees, but also on sandy, stony or rocky ground, often near craters and solfataras, where it occurs as very low, creeping, small-leafed, exposed forms. The root system extends near the surface of the ground and the stems root adventitiously; locally common ** * Rhododendron retusum * var. * trichostylum * ** On forested slopes
Vireya retusa Blume, Bijdr. 1826. 856. Azalea retusa (Blume) Kuntze, Rev. Gen. Pl. 1891. 2: 386.
Argent, G. (2006) Rhododendrons of subgenus Vireya. RHS:London. Page:43