SALICACE^E 



133 



11. Populus McDougallii Rose. 



Leaves broadly ovate, abruptly short-pointed or acute at apex, broadly or acutely 

 cuneate or truncate, or on vigorous shoots rarely slightly cordate at base, finely or often 

 coarsely crenately serrate, bluish green, thin, pubescent on the under sides of the midrib 

 and primary veins early in the season, otherwise glabrous, lj'-3' long and broad, with slen- 

 der midribs and veins; petioles slender, slightly compressed, pubescent early in the season, 

 becoming glabrous, H'-2' in length. Flowers not seen. Fruit: aments glabrous, short- 

 stalked, 2'-2|' long; fruit ovoid and acute at apex to ellipsoidal and acute or acuminate at 

 ends, glabrous, slightly pitted, thin-walled, 3-valved, ^'-\' long; disk not more than \' 

 in diameter; pedicels glabrous, \'-\' in length; seeds oblong-ovoid, acuminate, \' long. 



Fig. 127 



A tree rarely 90-110 high, usually much smaller, with erect branches and slender 

 branchlets pubescent or puberulous when they first appear, sometimes becoming glabrous 

 during their first season, and sometimes pubescent during two years. 



Distribution. Banks of streams and springs, San Bernardino County, California (Cot- 

 tonwood Springs, Meca, etc.), and eastward to the bottoms of the Colorado River from 

 Clark County, Nevada, to Yuma, Arizona, and probably the only Cottonwood in this 

 arid region. 



Often planted as a street tree in the towns of southwestern California and of adjacent 

 Nevada and Arizona. 



12. Populus Wislizenii Sarg. Cottonwood. 



Leaves broadly deltoid, abruptly short- or long-pointed at apex, truncate or sometimes 

 cordate at the broad entire base, coarsely and irregularly crenately serrate except toward 

 the entire apex, coriaceous, glabrous, yellow-green and lustrous, 2'-2|' long, usually about 

 3' wide, with a slender yellow midrib, thin remote primary veins and conspicuous reticulate 

 veinlets; petioles slender, glabrous, l|'-2' long; on vigorous shoots often 3^'-4' long and 

 wide with petioles 3'-4' in length. Flowers: aments 2'-4' long, the pistillate becoming 

 4'-5' long before the fruit ripens; scales scarious, light red, divided at the apex into elon- 

 gated filiform lobes; disk of the staminate flower broad and oblique; stamens numerous, 

 with large oblong anthers and short filaments; disk of the pistillate flower cup-shaped, 





