198 MISC. PUBLICATION 303, U. S. DBPT. OF AGRICULTURE 



of importance commercially ; root sprouts formed ; seed vitality transient, much 

 abortive ; generally a transient species invading and quickly occupying burned 

 and logged areas and soon giving way to other species ; the shade of these trees 

 is never dense in spite of the closeness of stands ; frequently supports an under- 

 story of weeds. 



Stomach records: Three species of birds, including ruffed grouse and sharp- 

 tailed grouse ; black-tailed deer, northern white-tailed deer, mountain sheep, 

 plains white-tailed deer ; composed 3.2 percent of winter food of northern sharp- 

 tailed grouse in Quebec and Ontario. Observations: Highly palatable to captive 

 deer ; pika ; mountain beaver ; white-tailed deer ; important food of snowshoe 

 hare; important browse of moose; important food of Pacific coast and Shasta 

 beaver ; of outstanding importance as browse for mule deer ; red squirrel ; the 

 principal food of beaver throughout its range ; black bear, cottontail rabbit, 

 porcupine. Frequently supports understories of weeds and browse highly 

 esteemed by livestock. Very palatable to sheep and goats. 



Populus trichocarpa Torr. and Gray. Black cottonwood. 



Range : 1, 2, 3, 4, 5, 6, 7, 8, 12, 13. 

 Site: Moist, sun. 

 Fruit : Capsule. 



A large tree ; commonly occurs in sandy humus or gravel ; root system shallow ; 

 very rapid growing, longest-lived of the poplars although comparatively short- 

 lived; storm-damaged, not wind-firm; wood of importance commercially, espe- 

 cially for pulp; seed with a high percentage germination, vitality transient. 

 Stomach records: Ruffed grouse. 



Populus tweedyi Britt. Tweedy cottonwood. 



Range : 9. 



Site : Well-drained, moist, sun. 

 Fruit: Capsule. 

 A small to large tree. 



Populus vaneouveriana, see Populus tremuloides. 

 Populus virginiana, see Populus deltoides. 



Populus wislizenii (Wats.) Sarg. Valley cottonwood. 



P. fremontii wislizenii Wats. 

 Range: 11, 17. 



Site : Well-drained, moist, sun. 

 Fruit : Capsule. 



A large tree; commonly occurs in sandy soil; rapid growing in moist situa- 

 tions, slow in intermittently moist situations; short-lived, mud? cultivated 

 throughout New Mexico ; wood used locally, especially for fence posts. Eaten 

 by cattle. 



Porlieria angustifolia (Engelm.) Gray. Soap-bush. 



Guiacum angustifolium Engelm. 

 Range : 11, 17, 20. 

 Site: Dry, well-drained, sun. 

 Fruit : Capsule. 



A large shrub to small tree ; evergreen ; branches rigid, spreading or strag- 

 gling; wood very durable, used locally for fence posts. An important honey 

 plant. 



Potentilla fruticosa L. Shrubby cinquefoil. 



Dasiphora fruticosa (L.) Rydb. 



Range : 4, 12, 13, 14, 15, 18, 21, 22, 23, 24, 25, 26, 27, 28. 

 Site : Dry, well-drained, moist, sun, shade. 

 Fruit: Achene. 



A small evergreen shrub ; flowers June-September ; often sprawling ; much 

 branched ; an aggressive species commonly invading pastures in New England, 

 but plowing and close pasturing have successfully checked its spread; some 

 14 varieties are in cultivation. 



Observations: Rarely browsed by moose; casually browsed by northern white- 

 tailed deer. Considered inferior forage for cattle, but of importance for sheep 

 and goats in the Southwest. 



Prinos coriacea, see Ilex coriacea. 



