BaLFouR—NEw SPECIES OF RHODODENDRON. 149 
Rh. cruentum, Lévi. (913). N.E. Yunnan:  Ta-hai-tze 
Plateau, 10,000 ft. (Maire, 
IQII.) 
Rh. Edgeworthit, Hook. f.  E. Himalaya: Sikkim, 7000- 
(1849). gooo ft. (Hooker f. 1848) ; 
Bhutan. (Griffith.) 
Rh. sciaphilum, Balf. f. et E. Upper Burma: Naung 
Ward (1917). Chaung Valley, 7000-8000 
ft. (Ward, 1914.) 
To Rh. Edgeworthit, which has been in cultivation since 1849, 
we now can add Rh. bullatum and Rh. Bureavi as plants in 
our gardens. 
The Edgeworthii series is marked by vegetative and floral 
characters illustrative of a true natural phylum. The plants 
seem to be frequently though not always epiphytic. Probably 
in their case, as in that of others, altitude may determine habitat 
of the plants and there can be little doubt that their epiphytism 
is favoured by their partnership with a fungal symbiont. 
The striking feature of all the Edgeworthii series is the 
golden brown or red indumentum which completely encloses 
with a thick felt every aerial radial organ of their bodies— 
stem—pedicels—petioles—ovary—base of style—fruit—and 
covers the under surface of the mature foliage-leaves and more 
or less that of the calyx. This indumentum in all the forms to 
a casual observation seems to consist of closely interlocking hairs 
Which can be readily removed, But similarity in general form 
is arrived at by different paths, Closer examination shows that 
this superficial ‘ wool” layer is not always made of the same 
kind of thread, and, moreover, that it does not constitute the 
whole indumentum, which is bistrate. C. B. Clarke * has noted 
the bistrate character of the: indumentum of the leaves of Rh, 
Edgeworthit. He says: “There are round glandular scales 
beneath the wool of the leaves.” 
There are really two modifications of bistrate indumentum 
in the series. One found in Rh. bullatum, Rh. Edgeworthit, and 
Rh, sciaphilum, and we may designate it A. form; the other 
in Rh. Bureavi and Rh. cruentum, and we may call it B. 
form ;— 
A. form.—The upper stratum in this indumentum consists 
of many very long unbranched hairs, each tapering from a 
thicker base to a fine point. The base 1s composed of many 
elongated narrow cells, each with a thickish wall, lying parallel 
and forming a cord—fasciated, as it were—often with a core 
and a peripheral sheath; the number of these component cells 
* Clarke in Hook. f. Fl. Brit. Ind, iii. (1882), 469. 
