ur 
58 BALFOUR—NEW SPECIES OF RHODODENDRON. 
forms amongst the numerous Himalayan Rhododendrons that 
have been described as species, and now in the much larger 
field of Chinese Rhododen drons there is similar questioning. 
Dried herbarium specimens can only supply a part of the 
evidence that is required for the solving of a biological problem 
of this kind ; the other part must come from direct observation 
by the collector in the habitats of the plant, and from ob- 
servation and experimental work in our gardens. The cases 
presented here offer elements in a simple form for such experl- 
mental work which, if rightly pursued, may furnish us with 
proof that the plants we have been discussing are illustrations 
of natural hybrids amongst Rhododendrons. 
Rhododendron dryophyllum,* Balf. f. et Forrest. 
Eglandular shrub as much as 3 m. high with rigid straight 
branches. Branches of the year as much as 3 mm. in diameter 
enwrapped in a buff-coloured thin indumentum of  short- 
stalked rosette-hairs, some with long intertwining vesicular 
branches, others with short ones, the indumentum persisting 
more or less for several years appearing as a black coating on 
the reddened older parts of the branches. Foliage-buds narrow 
fusiform pointed somewhat chestnut-brown ; outer scale-leaves 
crustaceous more or less rounded and apiculate or tailed rufous- 
brown keeled, about 7 mm. long; inner scale-leaves oblong-oval 
or obovate ; innermost ligulate-spathulate mucronate mem- 
branous yellowish about 2.5 cm. long, clad like all scale-leaves 
with a thin tomentose indumentum of branched floccose hairs 
at first white becoming red and greasy, very dense around the 
* Sertetics. with leaves like oak—the leaves are quite like those of many 
“Pos dodendron od ae Balf. f. et Forrest.—Frutex ad 3 m. altus 
it 
oblonga vel oblongo-lanceolata ad 14 cm. longa 3.5 cm. lata subrostrata, margine 
plana, basi cuneata ; supra nitens brunnea (in See, pilorum vestigiis notata, 
costa media sulcata venis primariis utrinque ad 18 obscuris; infra flavido-fulva 
