64 MISC. PUBLICATION 101, U. S. DEPT. OF AGRICULTURE 
its palatability was found to be poor, even though it was browsed — 
sparingly by sheep. i 
River hawthorn (C. rivularis) is very close to black hawthorn 
botanically and by some authors considered a variety of it. This is 
a Rocky Mountain species ranging along stream courses and in ~ 
moist valley lands from Idaho to Nevada, New Mexico, and Wyo- — 
ming, mostly between elevations of 3,000 (in the north) and 8,000 — 
feet. It is not usually so tall as C. douglasit and has slender but — 
short and relatively sparse spines. River hawthorn sometimes occurs — 
in rather dense stands in the Wasatch Mountains, but as a rule is — 
found as scattered individuals or in clumps. In some places it fur- 
nishes fair to fairly good cattle and sheep browse. 
MOUNTAIN-ASHES (SORBUS SPP.) 
About a dozen species of Sorbus occur in the northern hemisphere, 
seven or eight of these being found in the Western States. Although 
probably all these species have some local forage significance, only 
three are common enough to deserve detailed notice here: S. occiden- 
talis, 8S. scopulina, and S. sitchensis. All three of these species, re- 
ferred to indiscriminately as western mountain-ash, are constantly 
confused with each other, and with a fourth less common, S. sam- 
bucifolia, apparently a distinct species of Kamchatka and eastern 
Siberia. Because of this confusion, in which botanist and layman 
are alike involved, it is practically impossible to define with any 
accuracy the botanical range of any of these species. The following 
key will be found useful in attempts to identify the three species 
discussed below: 
Plant low (mostly about 40 inches high, rarely as much as 9 feet tall). 
Subalpine-alpine species. Leaflets dull above, serrate toothed toward the 
tip only. Fruit purplish, somewhat glaucous. Additional characters: Leaf- 
lets obtuse or rounded at apex. Inflorescence small and usually round-topped. 
Fruit ‘often, pear shaped 2— 22222 22 Ss See ee ee een ee S. occidentalis. 
Plants taller (about 8 to 16 feet high). Montane, but not subalpine-alpine 
species. Leaflets shining above, serrate toothed their whole length or prac- 
tically so. Fruit red, not glaucous. 
Rocky Mountain and eastern species. Leaflets rather thickish, mostly 
of an elliptic or oblong lance shaped type, and two or three times as 
long as bread, acute (occasionally obtusish) at the tip. Fruit orange 
to searlet and about one-third inch in diameter when mature. (Pos- 
sibly only an eastern variety or form of S. sitchensis)____S. scopulina. 
Pacific species. Leaflets mostly thin, usually narrow lance shaped, about 
five or six times longer than broad, and long-tapered. Fruit coral-red, 
about one-fourth inch in diameter when mature__________ S. sitchensis. 
In marked distinction to a number of Old World Sorbi, the fruits 
of our native mountain-ashes are sour and inedible, and birds usually 
do not eat them unless other fruit is lacking. 
Alpine mountain-ash (S. occidentalis), a fragrant-flowered shrub 
2 to 9 feet high, is a high-mountain species, occurring near, at, or 
above timber line (Hudsonian and Arctic-Alpine zones), and rang- 
ing from Alaska and Yukon to western Montana and Oregon. 
Opinions vary somewhat as to its browse value, but there is no doubt 
that in some places it is important, although for only a portion of 
the grazing season. In parts of Idaho it is held to be good or very 
good browse on sheep and common-use range, at least toward the 
