13. Cones 1H-2J^' long, falling in one year and leaving 

 basal scaJes on limb; scales red-brown and unarmed; 

 southern Canada to Minnesota and West Virginia . . . 

 P. resinosa. Red Pine, p. 17. 



12. Needles 1-3" long. 



14. Bark distinctly orange-colored; cones 1^-2 3^' long, 

 unsymmetrical, opening at maturity and falling when 

 ripe; scales often pyramidally thickened; widely 



planted and naturalized in Northeast 



P. sylvestris, Scotch Pine, p. 17. 



14. Bark not distinctly orange-colored; cones long per- 

 sistent; scales not pyramidally thickened. 

 15. Cones 2-3 3^" long, heavy; scales with much 

 thickened ends and armed with conspicuous sharp 

 spurs; Appalachian Moimtains, New Jersey to 



Georgia 



P. pungens. Table Mountain Pine, p. 29. 



15. Cones 13^-2* long; thin-scaled, with slender or 

 minute prickles. 



16. Cones strongly incurved, commonly remaining 

 closed; scales irregularly developed; Canada 

 to New York, Indiana, Wisconsin, and Minne- 

 sota P. banksiana. Jack Pine, p. 19. 



16. Cones symmetrical, opening at matiuity; New 

 York to Indiana, south to Georgia and Missis- 

 sippi .... P. virginiana, Virginia Pine, p. 19. 

 Southern Yellow Pines (Gulf and South Atlantic States). 

 17. Needles 6-18" long, in 3's (2's and 3's in Slash Pine). 



18. Cones 2-2 3^" long and broad, often remaining closed, long 



persistent; needles 6-8" long; New Jersey to Florida 



P. serotina. Pond Pine, p. 21. 



18. Cones 2-10" long, much longer than broad, opening at 

 matxirity and not persistent. 



19. Needles 8-18" long; cone 6-10" long; conspicuous 

 thick twigs and large silvery-white buds; Virginia to 



Florida and Texas 



P. palustris, Longleaf Pine, p. 27. 



19. Needles 6—12" long; cone 2-6" long; twigs not con- 

 spicuously stout; buds red-brown. 



20. Needles in 3's, 6-9" long; cone light brown with 

 stout spine; New Jersey to Oklahoma and Texas 



P. taeda, Loblolly Pine, p. 25. 



20. Needles in 2's and 3's, 8-12" long; cone chocolate- 

 brown with small spine or prickle; South Carolina 



to Louisiana P. elHottii, Slash Pine, p. 29. 



17. Needles 1 3^-5" long, in 2's (2's and 3's in Shortleaf Pine). 

 21. Needles 3-5" long, in 2's and 3's, widely distributed on dry 



soils ; New York to Missouri and south 



P. echinata, Shortleaf Pine, p. 23. 



21. Needles 1 3^-3 3^" long, in 2's. 



22. Cone 2-3 3^" long, often remaining closed and per- 

 sistent for years; dry sandy soils in Florida 



P. clausa. Sand Pine, p. 25. 



22. Cone 3^-2" long, opening at maturity and falling in 



few years ; coastal bottomlands 



P. glabra. Spruce Pine, p. 23. 



Western Yellow Pines (region west of Great Plains). 

 23. Needles in 5's. 



24. Needles 5-7" long; cones thin-scaled, 2-3 3^" long; Arizona 



and New Mexico 



P. ponder osa arizonica, Arizona Pine, p. 31. 



24. Needles 8-13" long; cones thick-scaled, 4-6" long; southern 

 California P. torreyana, Torrey Pine, p. 41. 



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