Popnhis. SALICACE.E. gj^ 



2. POPULUS, Tourn. rorLAit. Cottonwood. Asif.n. 



Aincnts preceding the leaves, pendulons, axillary, sessile or nearly so, the pistil- 

 late longest and loosely Howered : bracts lacerately toothed or fringed. Stamens 

 few to many, inserted on the face of an oblicpiely trn^icate disk, with distinct filiform 

 filaments and purple anthers. Ovary surrounded by a more or less cup-shaped disk : 

 styles 2 to 4, often united at base, lobed or divided. Capsule ovate-oblong to glo- 

 bose, 2-4-valved. — Trees with scaly and often resinous buds, caducous stipules, 

 and glandular-crenato leaves. — WesuKud in JJC. I'rodr. xvil ',Vi:\. 



AliDut 20 siiccics, of nnrllicrn c\tra-troiii<-al regions, riiUMJIv divided lietweeii the Old niid New 

 AVoilds. The wood is li.!,'lit(oloie<l, soft and light, durable if kept dry. The fragrant resinous bal- 

 sam, whieh eoals abundantly the buds of some species, is occasionally eolleetcd for medicinal use. 



* Stijldi 2, with 2 or 3 linear lobes: capsules small, ohloiuj-conlcah thhi, 2-valoed : 



stamens G /o 20: leaves hroadbj ovate, crenulate ; petioles jtattened. 



1. P. tremuloides, Michx. Trunk straight and slender, 20 to 50 feet high, 

 ■with smooth grayi.sh-winte bark ; branches not angled : buds long, viscid : leaves 

 round ovate, 1 to 3 inches in diameter, very shortly acuminate, slightly cordate to 

 somewhat cuneate at base, villous-ciliate when young; petioles slender, much flat- 

 tened above, as long as the blade : staminatc aments dense, an incli or two long, 

 with longciliatc l)racts : stamens 7 to 10, with very short lilaments : pistillate 

 aments 2 to 4 inches long, the rha(;his pubescent : disk small : cai)sules on short 

 slender pedicels (a half to one line long), glabrous, 2 lines long : seed light brown, 

 a half line long. — Michx. f. Arb. Amer. iii. 285, t. 8, tig. 1. 



From the Sacramento eastward across the continent and northward through liritish America to 

 the Arctic Ocean ; in the I{ocky Mountains as far south as New Mexico. I'sually in dense copses, 

 covering moist slopes and Iwttoms, at an altitude varying from (5,000 to 10,000 feet or more, 

 {icncrally known as " (^)uaking Asp." 



* * Styles 2 to 4, with dilated lobes : eapsitles large, subfjlnbose to ovate-oblonrj, 



2 - 4:-ralved, often tltlek. 



-K- Stamens itsaalhf 20 to 30 : leaves cordate or ovate to lanceolate, frenate ; 



jieflolcs terete: seed a line lony : yomuj bark brownish. 



2. P. trichocarpa, Torr. Sz dray. A tree of ojien growth, 30 to 50 feet high 

 or more, with thick cracked l)ark, the young barren branches somewhat angled: 

 buds shining and viscid : leaves broadly ovate to oblong-lanceolate, acuminate, cor- 

 date (sometimes rounded) at base, 2 to 4 inches long, finely jjuberulent when young, 

 becoming somewhat lighter colonel beneath ; petioles usually an inch or two long : 

 staminate aments dense, 2 inches long ; bracts slightly villous; rhachis pubescent; 

 disk broad, somewhat pubescent ; filaments as long as the antiiers : pistillate aments 

 2 inches or more (becoming G inches) long, witii pubescent rhachis, the bracts and 

 much dilated disk nearly glabrous : ovary densely pubescent ; styles 3, broadly di- 

 lated and lobed : capsules nearly .sessile, sul)globose, pubescent, 3-valved, 3 lines 

 in diameter: seed light-ccdored. — Hook. Icon. t. 878 ; Watson, Hot. King Exped. 

 328, and Amer. Jourii. Sci. 3 s(!r. xv. 13(5. P. bahamifera, var. y, Hook. Fl. IJor.- 

 Am. ii. 151. /'. bahamifrra, var. {]) Callfornira, Watson, 1. c. 135. 



Var. cupulata, Watson, 1. c. 13G. liisk of the pistillate flowers very large and 

 somewhat iierbaceous, carapanulate and twice longer than the ovary, pubescent : 

 bracts somewhat villous, and joedicels a line or two long. 



From San Diego northward to British Columbia and extending into Western Nevada : the vari- 

 ety from Plumas Countv, J/r.i. Jusfiii. Acconling to Douglas it attains in Washington Territory 

 a height of (JO to 100 feet, with a diameter of 2 to 6 feet. I-ike the following species it is gen- 

 erally found scattered or in open groves along stream-banks and in river bottoms, at an altitude 

 not exceeding 6,000 feet. The narrow-leaved species of the Ilocky Jlountains (P. iiutjnsti/olin, 

 James) is found in the mountains of Central Nevada (Shoshone Mountains, IVcUsoii), and uorth- 

 westward to the valley of the Columbia. 



