3882 FOREST CULTURE AND 
Rheum australe, Don.* (R. Emodi, Wall.; R. Web- 
bianum, Royle.) — Himalayan regions, up to 16,000 
feet. From this species at least a portion of the me- 
dicinal rhubarb is obtained. Most likely several spe- 
cies furnish rhubarb- root, and its quality depends 
probably much on the climatic region and the geologic 
formation in which the plant grows. Should we wish 
to cultivate any species here for superior medicinal 
roots, then, clearly, localities in our higher and drier 
alpine tracts should be chosen for the purpose. Hayne 
regards the presence of much yellowish pigment in 
the seed-shell as indicating a good medicinal rhubarb- 
plant. As much as 5 lbs. of the dried drug are ob- 
tained from a single plant, several years old. An 
important orange-red crystalline substance, Emodin, 
allied to Crysophanie acid, occurs in genuine rhubarb. 
Rheum Rhaponticum, L.—From the Volga to Cen- 
tral Asia. This species, together with R. Tataricum, 
L. fil., R. undulatum, L., and a few others, all Asiat- 
ic (one extending to Japan), provide their acidulous 
leaf-stalks and unexpanded flower - mass for culinary 
purposes. Rhubarb-leaves can also be used in the 
manner of spinach. R. palmatum, L., often consid- 
ered to yield the best rhubarb-root, is an insular plant 
of North-eastern Asia, but may, in the alpine deserts 
far inland, become a source of the genuine root, so 
long ascribed to it. That is the only one with deeply- 
jagged leaves. 
Rhus copallina, L. —North America, extending to 
Canada. A comparatively dwarf species. This can 
also be used for tanning. A resin for varnishes is 
also obtained from this shrub. 
Rhus Coriaria, L.*—The Tanner’s Sumach. Coun- 
