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Article from Bean's Trees and Shrubs Hardy in the British Isles
'Rhododendron ciliicalyx' from the website Trees and Shrubs Online (treesandshrubsonline.
Free-growing shrub; young shoots setose. Leaves 7-11 x 2.5-4 cm, elliptic to narrowly elliptic, apex acute, margin often slightly ciliate, upper surface with impressed midrib, lower surface brownish, with dense but not touching scales. Flowers (2-)3-5, in a loose inflorescence, slightly scented; calyx lobes to 6 mm, ciliate; corolla white or pink, broadly funnel-shaped, 50-60 mm, outer surface usually lacking scales, pubescent below; stamens c.10; ovary scaly, impressed below the style that is scaly and pubescent towards the base. Flowering March-May. Royal Horticultural Society (1997)
Distribution China Yunnan, Guizhou
Habitat c.2,400 m
RHS Hardiness Rating H3
Awards AM 1923 (Oxford Botanic Garden). AM 1975 (G. Gorer, Sunte House, Haywards Heath) to a clone 'Walter Maynard'; flowers white, yellow-green externally, at base mid-ribs of corolla lobes soft red-purple, upper throat flushed yellow-green.
Conservation status Data deficient (DD)
Taxonomic note This species is allied to R. pachypodum but may be distinguished by the corolla that usually lacks scales on the outer surface. Royal Horticultural Society (1997)
An evergreen shrub of rather diffuse habit, 8 to 10 ft high; young shoots bristly and slightly scaly. Leaves narrowly oval, or oblanceolate, tapered at both ends, pointed, 21⁄2 to 41⁄2 in. long, 1 to 2 in. wide, dark glossy green above, glaucous-green beneath and thickly sprinkled with golden-brown scales; stalk 1⁄3 to 1⁄2 in. long, bristly and slightly scaly. Flowers produced in March and April in a terminal truss of usually three blossoms. Flower-stalks 1⁄2 in. long, stout, scaly. Calyx five-lobed, the lobes 1⁄8 in. long, conspicuously fringed with white bristles 1⁄8 in. long. Corolla pure white except for a yellow stain on the upper side of the tube; the base is funnel-shaped, the five rounded wavy lobes spreading and giving the flower a diameter of 4 in. Stamens ten, about 2 in. long, white, very hairy at the base. Ovary scaly; style 21⁄2 in. long, scaly at the base. Bot. Mag., t. 7782. (s. Maddenii ss. Ciliicalyx)
R. ciliicalyx was discovered by the Abbé Delavay in 1884 in W. Yunnan, in the mountains east of Lankiung (north of Lake Tali), and was introduced from Paris to Kew in 1892, first flowering there in 1900. It was later reintroduced by Forrest from the borders between Yunnan and Burma and more recently by Kingdon Ward from the Triangle, during his last expedition to Burma (1953). According to him R. ciliicalyx is not usually an epiphyte. ‘On the contrary, it is more often a slim shrub ten to twelve feet high … though it needs strong support from the surrounding thicket to keep it upright. Out of bloom, its shining plum-purple bark betrays it… . Very occasionally it is an epiphytic shrub, appearing as a pale summer cloud in a big tree’ (Return to the Irrawaddy, p. 161).
This beautiful species, one of the very finest of white rhododendrons, grows well in the Temperate House at Kew, where it has protection from more than one or two degrees of frost. Here it is covered with blossom every spring. It is only likely to succeed out-of-doors in the milder parts of Cornwall and similar places. The flowers are sometimes pink and they have a faint sweet fragrance. It is closely related to the much hardier Himalayan R. ciliatum, whose style has no scales and whose habit is dwarfer, more spreading and bushy. The bristly calyx is distinctive.
Although not the oldest species in its group, R. ciliicalyx has been taken as the ‘type’ of a large and taxonomically difficult subseries of the Maddenii series. In this some thirty-five species have been placed, many of them distinguished by unreliable characters. In a cursory study of the subseries, Dr Sleumer has reduced the number to twenty and remarks that still more drastic reduction may be necessary (‘The Genus Rhododendron in Indochina and Siam’, Blumea, Suppl. IV (1958), pp. 40-7). There can be no doubt that most of his judgements will be upheld when the group is subjected to a detailed revision, but in the meantime it seems best to maintain those of the reduced species which are familiar in cultivation. See also R. johnstoneanum and R. veitchianum.
To the description should be added that the corolla is downy (but not scaly) outside near the base and the ovary tapered at the apex into the style. The synonym R. atentsiense should be deleted.
If the treatment of the Maddenia subsection in the Edinburgh revision is followed, the statement that Forrest reintroduced R. ciliicalyx from the Yunnan-Burma border is incorrect, since at least eight of his collections originally identified as R. ciliicalyx are referred by Dr Cullen to his new species R. pseudociliipes (see below). It is also very doubtful whether Kingdon Ward reintroduced R. ciliicalyx from The Triangle of northern Burma, though three of his seed-collections are listed as that species in the R.H.S. Handbook. As understood by Dr Cullen, R. ciliicalyx is confined to Yunnan, where it has a limited distribution.
Of the species mentioned under R. ciliicalyx on pages 632-3, three – R. carneum, R. dendricola and R. supranubium – were sunk in this species by Dr Sleumer, while R. scottianum was considered by Dr Hutchinson, who described it, to be very near to that species. However, these four are quite differently disposed of in the Edinburgh revision. R. carneum is accepted as a distinct species. It is indeed near to R. ciliicalyx. Of the other three, R. dendricola is accepted, and is further mentioned in this supplement under R. johnstoneanum. As for R. scottianum and R. supranubium, these are sunk in R. pachypodum (mentioned in the main work under R. burmanicum), for which see below.
R. ciliicalyx is the central species of Dr Cullen’s Ciliicalyx aggregate, a group of ‘weakly delimited’ species, mostly of Yunnan, but one extending into north-east Burma, and another (R. lyi) ranging from Kweichow into Vietnam and Laos. The most important are:
† R. pachypodum Balf. f. & W. W. Sm. R. piliicalyx Hutch.; R. supranubium Hutch. (type only); R. scottianum Hutch. – A shrub of variable habit according to locality; branchlets bristly only when young. Leaves elliptic or inclining to obovate, to about 4 in. long and 15⁄8 in. wide, densely to moderately scaly beneath. Inflorescence of three to five flowers. Calyx usually obscurely lobed, bristly at the edge. Corolla 2 to 3 in. long, white or pink-flushed, with a yellow blotch, scaly outside and also downy near the base.
A native of Yunnan and north-east Burma. The type was collected by Forrest on the western flank of the Tali range (F. 11547) and introduced under that number (the details of the type-locality given in Rev. 1, p. 53 are wrong, owing to a printing error). Seed of R. pachypodum in the original sense was also sent under F. 16032 and KW 3776. Forrest’s introductions from the Tali range were from altitudes of up to about 10,000 ft and so might be moderately hardy in the milder parts, as might the 1981 introduction by the Sino-British expedition to the range (now called Cangshan). But R. pachypodum in the narrow sense has never been common in cultivation.
Plants previously grown as R. scottianum are from Forrest 7516 collected in the Tengyueh (Tengchong) area of western Yunnan (and possibly from Rock 25235). The ‘scottianum’ form is finer, but came from about 6,000 ft and is definitely for greenhouses.
With regard to the synonym R supranubium, it should be noted that this refers to the type-collections from the eastern side of the Tali range. Plants raised from F.6764, the introduction from the type-locality of R. supranubium, would therefore be R. pachypodum. But plants from Forrest 17900 and Farrer & Cox 848 are R. pseudociliipes (see below) and KW 21512 is R. dendricola (these numbers are mentioned since they have hitherto been identified as R. supranubium).
† R. pseudociliipes Cullen R. ciliipes Hutch. (in part, paratype only); R. supranubium auct., not Franch. – This new species, which is clearly near to R. pachypodum (and to R. supranubium, which Dr Cullen includes in this species), differs in the fringe of bristles on the calyx being soon deciduous, the shorter leaves and a reduced inflorescence with only a single or two flowers. Native of western and north-western Yunnan and bordering parts of Burma; described from Forrest 17900, collected on the Nmai Hka-Salween divide, and evidently a fairly common species, to which numerous Forrest collections are referred by Dr Cullen (Rev. 1, 172-6). If this species is in cultivation it would be probably either as R. supranubium or as R. ciliicalyx. To it Dr Cullen also refers Farrer and Cox 848 from the Burma-Yunnan frontier. It is, incidentally, puzzling that so many Forrest collections identified by Dr Cullen as R. pseudociliipes should be listed in the R.H.S. Species Handbook as R. ciliicalyx, a species from which it is obviously distinct. Possibly ‘R. ciliicalyx’ is an old error for ‘Ciliicalyx subseries’ or ‘R. ciliicalyx aff.’
Two other species in the Ciliicalyx aggregate are:
† R. roseatum Hutch. R. lasiopodum Hutch. – Near to R. pachypodum, but with a more westerly distribution, being confined to the Shweli-Salween divide, and differing mainly in its foliage, the leaves being ovate, laxly scaly beneath, against more or less elliptic and more densely scaly beneath in R. pachypodum. In cultivation, but tender.
R. lyi Lévl. – This is mentioned on page 694, under R. jobnstoneanum, the species in which it was sunk by Dr Sleumer. It differs from all the other species in the aggregate in its permanently bristly stems.