l^fioboDenbron ^ocietp ^otEsi. 
Name and date of description. 
R. PREPTUM, Balf. f. et 
Forrest (1920)* 
R. REGALE, Balf. f. et Ward 
(1920)* 
R. Rex, LeveilU (1914) 
R. SINOFALCONERI, Balf. f. . . 
(1916) 
Distribution. 
Discoverer. 
N.E. Upper Burma : N’Maikha Forrest (1919) 
divide, 11,000 ft. 
N.E. Upper Burma : Htawjaw, Ward (1914) 
Valley of Naum-Chaung, 
over 10,000 ft. 
N.E. Yunnan : Mt. lo-chou, Maire (1911) 
3,200 m. 
S.E. Yunnaji: N. of Mengtsz, 
9,000 ft. 
Henry (before 
1898) 
Rhododendron ari'Zelum, Balf. f. et Forrest. 
This species was discovered by Forrest in June, 1917, at an elevation of 
11-12,000 feet, on the Shweli-Salween divide in Western Yunnan. He describes 
it as a shrub attaining some 20 feet in height bearing fleshy pale-yellow flowers 
with rose or crimson at the base. The specimens first collected and also those of 
a later gathering in July, 1917, are in full flower, suggesting therefore a late- 
flowering species for our gardens when it comes into cultivation, as it will from 
Forrest’s seeds. Plants of the species were found in April, 1919, by Farrer, as 
one of the prevailing Rhododendrons at 9,500-10,500 feet elevation on the 
Hpimaw Pass in N.E. Upper Burma, a station not far to the west of Forrest’s 
area of collecting, and he speaks of it as a low many-branched tree with thick 
trusses of dead creamy-white flowers, without scent, just coming into flower on 
April 20th. Its flowering period would appear to be a prolonged one. The 
leaves of the species are smaller—at most in our specimens 18 cm. long by 8 cm. 
broad—than in some of the members of the series, with the wrinkhng of the upper 
surface only slightly developed. The underleaf surface is smooth, densely 
covered all over (midrib and primary veins included) in a bright rusty indu¬ 
mentum which seems to be very persistent. The cup-hairs of the upper stratum 
of indumentum are of the funnel-type with short pluricellular stalk and the cup- 
wall is built up of elongated cells and is ridged by bands of thicker-walled ones, 
from which and from the margin of the cup many branches proceed. So many 
of these branches are there the cup-form sometimes is obscured. The general 
surface is a woolly one through interlocking of these hairs. The flower-truss 
has some 15 or more flowers, when young forming a globose bud. The corolla is 
of fair size about 4.5 cm. long and 8-lobed. The filaments of the 16 stamens 
are slightly puberulous above the base. The ovar}^ has 12-15 chambers, its 
outside densely clad with short-stalked branched hairs forming a close tomentum, 
each hair comparable in form to a pollard willow with stem and erect ascending 
branches. The ovary is never glandular. The capsule is curved about 3.5 cm. 
long and 1 cm. in diameter with orange-coloured tomentum. The species is the 
nearest approach amongst the Chinese forms to R. Falconeri of the Himalaya, 
much nearer than the plant named R. sinof.^lconeri. It is, how'ever, as are all 
* Description of this species will appear in an early number of Notes from the 
Royal Botanic Garden, Edinburgh. 
208 
