leaf blade, 4-6.5 cm. long; aments 4-6 cm. long; floral bracts cuneate, deeply 

 divided to near the middle into 3 to 5 triangular-lanceolate lobes, fringed with long 

 hairs; staminate aments densely flowered and cylindric. with short pedicels and 

 small oblique disks that support 6 to 12 stamens; pistillate aments more laxly 

 flowered, with mature pedicels 2-3 mm. long and oblique somewhat crenulate 

 disks 2-3 mm. in diameter; ovary conical, crowned by a thick short style and 2 

 erect thickened stigmas that are divided above into linear divergent lobes; fruits 

 ellipsoid-conic, thin-walled, 6-9 mm. long, on pedicels 2-3 mm. long; seeds 

 obovate, light-brown, about 1 mm. long. Incl. [var.] aurea (Tidestr.) Daniels. 



Apparently confined to the highest mts. in the Tex. Trans-Pecos where it grows 

 in ravines and on talus slopes above 7,000 ft. alt.; common in high mts., in bogs, 

 swamps and wet meadows of N. M. and Ariz. 



This species is probably the most widespread tree in North America. It occurs 

 in most of Canada and Alaska and throughout the United States, except in the 

 southeast, and southward into northern Mexico it is found only in the high 

 mountains. The leaves turn an intense bright yellow or orange-yellow in autumn. 

 It flowers and fruits in the spring in its range. The slightest breeze causes move- 

 ment of the leaves, hence the common name, "quaking aspen." 



2. Salix L. Willow 



Prostrate to ascending or erect shrubs to large trees, to 36 m. or more in height; 

 budscale one, with an adhering inner membrane; leaf blades variable, linear, 

 lanceolate, oblanceolate, elliptic or oblong, petiolate, often persistently stipulate, 

 green or glaucous on the lower surface, hairy to glabrous, the margins entire or 

 somewhat revolute, denticulate, serrulate, crenate, undulate or undulate-serrulate; 

 aments precocious, coetaneous or serotinous, ascending, divaricate or somewhat re- 

 curved (never pendulous), 1-10 cm. or more long, slender and flexuous to stout 

 and dense; flower scales entire to erose-toothed, yellowish to black, mostly hairy, 

 tardily deciduous or persistent; stamens 2 (sometimes united) to 7 or 8, with 1 

 ventral and sometimes 1 dorsal gland; capsules with 2 valves recurving at maturity, 

 lanceolate to ovoid, 2-9 mm. long, hairy to glabrous, sessile or pedicelled (0.5-3 

 mm. long), with 1 ventral gland and sometimes 1 dorsal gland; style 1 (sometimes 

 wanting), entire or more or less divided; stigmas 2, entire or more or less divided; 

 without a disk; seeds numerous, minute, 0.8-1.2 mm. long, oblong, bearing a tuft 

 of silky hairs at base. 



A genus of about 500 species, widely distributed throughout the North 

 Temperate and Arctic zones, a few in the American tropics and Southern Hemis- 

 phere. 



Many of the species produce vigorous shoots that may have much larger and 

 often more toothed leaves than on the mature plant, and the stipules may be 

 greatly enlarged and even foliaceous. The shape and measurements of all organs 

 given in our descriptions are from mature plants. 



The buds and twigs are the main parts of these plants that are eaten by 

 various game birds and songbirds, while not only these parts but also the bark 

 and foliage are eaten by various animal life, including, deer, elk, beaver, muskrat, 

 rabbit and squirrel. 



I. Distribution in Oklahoma and Texas (p. 752) 



II. Distribution in New Mexico and Arizona (p. 755) 



Key Based on Vegetative Characters (for Oklahoma and Texas species) 



A. Leaves narrowly lanceolate to lanceolate, acuminate to long-acuminate, 5-10 

 or 12 cm. long, finely serrulate, the vein islets beneath very small 

 (I) 



752 



