20 American Midland Naturalist Monograph No. 4 



Needles 2. 



Cones oval to globose; seeds large; occurs in the Southwest 



Pinon (P. edulii). 



Cones egg-shaped to globose; seeds small; not found in the South- 

 west parks. 



Needles 1 to 3 inches long; western species 



Lodgepole pine (P. contorla). 



Needles less than 2 inches long; eastern species 



Jack pine (P. Ban}(siana) . 



Needles 4 to 12 inches long; cones 2 to 10 inches long. 



Cones remaining closed and persistent for many years; rare in Yosemite 



National Park Knobone pine (P. altenuata). 



Cones opening at maturity and not long persistent. 



Trees with trunks branched below; bark dark gray, roughly furrowed; 

 cones with large seeds; lower elevations in \'osemite Na- 

 tional Park Digger pine (P. sabiniana). 



Trees with one main trunk; bark cinnamon or reddish-brown, broken 

 into irregular plates; cones with small seeds. 



Needles in 3's (or sometimes 2's), 5 to 10 inches long; cones 3 

 to 10 inches long; western species. 



Bark scales sulphur-yellow on under side; cones 3 to 6 



inches long; widespread in western parks 



Ponderosa pine (P. ponderosa). 



Bark scales reddish-brown on under side; ccnes 5 to 10 



inches long; in California parks 



Jeffrey pine (P. Jeffreyi). 



Needles in 2's, 4 to 6 inches long; conss about 2 inches long; 



eastern species Red pine (P. resinosa). 



Needles 5 in a bundle. 



Needles 2 to 5 inches long; cones cylindric, long-stalked and pendent from the 

 ends of the branches; trees of mostly lower or middle altitudes. 



Needles with conspicuous white lines on back; cones 12 to 18 inches long; 



in southern Cascades and Sierra Nevada parks 



Sugar pine (P. Lamberiiana) . 



Needles without white lines; cones 4 to 12 inches long. 



Needles 2 to 4 inches long; cones 5 to 12 inches long; western species 



- Western white pine (P. monticola). 



Needles 3 to 5 inches long; cones 4 to 8 inches long; eastern species 



Eastern white pine (P. strobus). 



Needles % to 21/2 inches long; cones egg-shaped or roundish to oblong, short- 

 stalked and spreading from ends of the branches ; high altitude trees. 



Cones narrowly egg-shaped to oblong, 2]/2 to 7 inches long. 



Needles 1 to 2J/2 inches long; cones to 7 inches long, the scales with- 

 out prickles; Rocky Mountains and in Sequoia National 

 Park Limber pine (P. flexilis). 



Needles % to 1 inch long; cones to 5 inches long, the scales with 

 minute slender prickles; in Kings Canyon and Sequoia 

 National Parks Foxtail pine (P. Dalfouriana'). 



Cones egg-shaped or roundish, 1 to 3|/2 inches long. 



Needles 1 to 2'/2 inches long; cones broadly egg-shaped to roundish, 

 the scales without prickles; in Pacific slope parks and parks 

 of Montana and Wyoming Whitebark pine (P. alhicaulis). 



