156 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
New Mexico: San Juan Valley; Santa Fe; Zuni; Mogollon Mountains; Burro 
Mountains; Black Range; Deming; Socorro; Mesilla Valley; above Tularosa. Along 
the larger streams, in the Lower and Upper Sonoran zones. 
The common “valley cottonwood,”’ as it is called by those who are acquainted with 
the ‘“‘mountain cottonwood,”’ is perhaps the best known tree of the State. It is doubt- 
less the most common shade tree of New Mexico, being used almost everywhere. It 
is very common along the broad flood plains of the Rio Grande and the San Juan, 
where it forms ‘‘bosques” of considerable extent. Besides its use as firewood and for 
fence posts, straight trunks are used by the Mexicans for the ‘‘vigas” or rafters of their 
houses. When stripped of their bark, the trees do not decay rapidly. 
3. Populus acuminata Rydb. Bull. Torrey Club 20: 50. 1893. 
Tyrr Locatiry: Carter Canyon, Scotts Bluff County, Nebraska. 
RanGE: Montana to New Mexico. 
New Mexico: Carrizo Mountains; Farmington; near Alma; mountains west of San 
Antonio; Cliff; Fort Bayard; Dog Spring; Kingston; Deming. Canyons and river 
valleys, in the Upper Sonoran Zone. 
This species grows in situations similar to those in which P. wislizeni is found, 
besides extending farther up into the mountains. At Deming and Silver City it is 
used as a shade tree along with the valley cottonwood and is probably equally valu- 
able for that purpose. 
4. Populus angustifolia James in Long, Exped. 1: 497. 1823. 
. MouNTAIN COTTONWOOD. 
TyPE LocALITy: Rocky Mountains. 
Range: British America to Nebraska, Utah, and New Mexico. 
New Mexico: Common in all the mountain ranges from the Black Range, Organ 
Mountains, and White Mountains northward. Canyons and along streams, in the 
Transition and Upper Sonoran zones. 
The mountain cottonwood or ‘‘ narrow-leaved cottonwood ” grows naturally in the 
mountains along streams, sometimes attaining a great size. It is also common along 
the valley of the San Juan in San Juan County. It is a rapid grower like its con- 
geners, and is worthy of much more extensive use than has so far been accorded it. 
2. SALIX L. Wi.ow. 
Shrubs or small trees, from a few centimeters to several meters high; leaves from 
narrowly linear to short-elliptic or obovate; flowers in aments, appearing before or 
with the leaves; perianth a single scale; stamens few; pistil single, with a gland at 
the base of the ovary, the stigma short; fruit a capsule, containing numerous very small 
hairy seeds. 
The plants of this genus occur at all levels in the State, but are always found where 
the ground water is abundant and near the surface during the growing season. 
KEY TO THE SPECIES. 
Leaves usually only about 3 times as long as broad, elliptic-oval 
to obovate, never narrowly lanceolate or-linear; capsules 
hairy (except in S. monticola). 
Styles obsolete, or less than 0.5 mm. long. 
Alpine plants less than 10 cm. high. ..........-.-.-.-- 1. S. savimontana. 
Small trees or shrubs, much more than 10 cm. high, at , 
middle elevations in the mountains. 
Aments slender, lax; scales pale; stigmas very short; 
leaves elliptic-lanceolate, acute............ 2. S. bebbiana. 
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