Rhododendron valentinianum Forr. ex Hutch.

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Article from Bean's Trees and Shrubs Hardy in the British Isles

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'Rhododendron valentinianum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-valentinianum/). Accessed 2020-01-28.

Genus

Infraspecifics

Other species in genus

Glossary

calyx
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
corolla
The inner whorl of the perianth. Composed of free or united petals often showy.
ovary
Lowest part of the carpel containing the ovules; later developing into the fruit.
bud
Immature shoot protected by scales that develops into leaves and/or flowers.
calyx
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
ciliate
Fringed with long hairs.
entire
With an unbroken margin.
glandular
Bearing glands.
style
Generally an elongated structure arising from the ovary bearing the stigma at its tip.
variety
(var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.

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Credits

Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Rhododendron valentinianum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/rhododendron/rhododendron-valentinianum/). Accessed 2020-01-28.

Small shrub, 0.3-1.3 m; young growth densely setose. Leaves 2.6-3.8(-5) x 1.6-2.2(-3.1) cm, elliptic, apex obtuse, margin entire, ciliate, upper surface with midrib impressed, lower surface brown, with dense overlapping unequal scales. Flowers (l-)2-6, in a loose terminal inflorescence, not scented; calyx 5-7 mm, ciliate; corolla bright yellow, funnel-campanulate, 20-32 mm, outer surface with tube pubescent and scales restricted to the lobes; stamens 10; ovary densely scaly, impressed below the style that is variably scaly towards the base. Flowering March-April. Royal Horticultural Society (1997)

Distribution  Myanmar N China SW Yunnan, Guizhou

Habitat 2,700-3,600 m

RHS Hardiness Rating H4

Awards AM 1933 (Hon. H.D. McLaren, Bodnant); flowers yellow.

Conservation status Near threatened (NT)

Taxonomic note This yellow-flowered species is allied to R. fletcherianum but differs in the entire leaves, with a dense brown covering of scales on the undersurface. It is one of the hardier members of Subsect. Maddenia that can be grown successfully outside in the more sheltered gardens of the S & W of Britain. The recently described var. oblongilobatum R.C.Fang is reported to be in cultivation. It differs from the type variety (as described above) in its. shorter (4-5 mm), oblong calyx lobes that are glandular-scaly, not ciliate. Royal Horticultural Society (1997)

An evergreen shrub 3 or 4 ft high; young shoots densely bristly and scaly beneath the bristles. Leaves oval inclined to oblong, 112 to 2 in. long, 34 to 1 in. wide, pale green and bristly above, nearly covered with tawny scales beneath, margins bristly; leaf-stalks 13 to 12 in. long, bristly and scaly. Flowers two to six in a close terminal cluster. Calyx 13 in. long, five-lobed, the lobes oblong, scaly outside and densely woolly-hairy on the margin. Corolla bright yellow, between funnel- and bell-shaped, about 112 in. long, five-lobed, densely scaly outside. Stamens ten, with white hairs at the lower part; anthers pink. Ovary and base of style scaly. Bot. Mag., n.s., t. 623. (s. Maddenii ss. Ciliicalyx)

R. valentinianum was discovered by Forrest in 1917 on the Shweli-Salween divide, Yunnan, near the border with Burma, growing in open scrub at 11,000 ft. In a note accompanying the original description, Sir Isaac Bayley Balfour remarked on the affinity between this species and the Himalayan R. ciliatum, but there are many differences apart from the obvious one of flower-colour, notably that the leaves are smaller in R. valentinianum and densely scaly beneath.

R. valentinianum is a charming species, but, although winter-hardy, it is bud-tender and is really seen to best advantage in a cool greenhouse except in the milder parts. Grown out-of-doors it needs a well-lighted position, otherwise it sets little flower-bud and becomes lanky in habit. It received an Award of Merit in 1936 when shown from Bodnant.


R fletcherianum Davidian

Fairly closely allied to R. valentinianum, but differing in the leaves being green and sparsely scaly beneath, with shallowly crenate margins, the more widely funnel-shaped corollas and bristly-hairy ovaries. The flowers are paler yellow, and the habit more erect. Bot. Mag., n.s., t. 508. It is allied to R. ciliatum – more closely than is R. valentinianum – but differs in flower-colour, the crenate leaves and narrower calyx-lobes. It was discovered by Dr Rock in 1932, growing on the Sola La in the Yunnan-Tibet borderland, at 13,500 to 14,000 ft, and introduced by him (Rock 22302). It was grown in gardens as Rock’s form of R. valentinianum until named and described as a new species in 1961.R. fletcherianum is hardy, but flowering as it does in March or April the display is often ruined by frost. It needs a sheltered position, but one where it receives abundant light. Award of Merit April 14, 1964, when shown by E. H. M. and P. A. Cox, Glendoick, Perthshire (clone ‘Yellow Bunting’, with primrose-yellow flowers).

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