2636 



PINUS 



PINUS 



OG. Tree an open pyramid. 



H. Lvs. bluish green .... 8. 

 HH. Lvs. bright green: 

 habit loose, with 

 wide-s preading 



branches 3. 



EE. Branchlets densely brownish 



tomentose 1. 



BEE. Branchlets pubescent or pu- 



berulous. 

 F. Needles slender, somewhat 



pendulous, 4-6 in. long. 11. 

 FF. Needles stiff, 1%~4 in. 



long. 

 o. Back of Ivs. with fine 



white lines 10. 



oo. Back of Ivs. usually not 



lined. 

 H. Color of Ivs. bluish 



or dark green 9. 



HH. Color of Ivs. bright 



green 2. 



DD. Length of Ivs. %-lii in.: Ivs. 

 usually twisted, forming 

 brush-like tufts at the end of 



the branchlets 5. 



cc. Edges of Ivs. entire. 



D. Lvs. lYz-S in. long 4. 



DD. Lvs. 1-1% in. long. 



E. Branchlets dark orange- 

 brown: Ivs. rigid 17. 



EE. Branchlets orange: Ivs. usu- 

 ally slender 18. 



BB. Sheaths persistent: fibro-vascular 



bundles 2: Ivs. 8-12 in. long, rigid 50. 

 AA. Number of Ivs. 8, or 4 or 1, only occa- 

 sionally 2 or 6. 

 B. Usually solitary, sometimes in 2's. . 15. 



BB. Usually 4, sometimes 8 or 5 12. 



BUB. Usually 8, occasionally 2. 



c. Fibro-vascular bundle 1: sheaths 



deciduous. 

 D. Margin of Ivs. entire: Ivs. 



%-2 in. long. 



E. Lvs. usually 3, 1-2 in. long. 13. 

 EE. Lvs. usually 2, %-!% in- 

 long 14. 



DD. Margin of Ivs. serrulate: Ivs. 



2-4 in. long 16. 



cc. Fibro-vascular bundles 2: sheaths 



persistent. 



D. Branchlets glaucous: Ivs. bluish 

 or grayish green (see also 

 No. S3.) 



E. Habit of Ivs. slender, droop- 

 ing 49. 



EE. Habit of Ivs. straight, stiff. 



F. Buds very resinous: Ivs. 



6-12 in. long, dark 



bluish green 48. 



FF. Buds not or little resinous: 

 Ivs. 5-8 in. long, pale 



bluish green 31. 



DD. Branchlets not glaucous: Ivs. 



dark yellow or bright green. 

 E. Habit of Ivs. slender, droop- 

 ing. _ 



F. Resin-ducts internal 34. 



FF. Resin-ducts external. 



G. Branchlets yellowish: 



buds brown 20. 



GG. Branchlets light yellow- 

 brown: buds bright 



chestnut-brown 21. 



EE. Habit of Ivs. stiff. 



F. Length of Ivs. 6-12^ in. 

 G. Resin-ducts internal: 

 buds cylindric, with 

 spreading scales: Ivs. 

 dark green, in 2's 

 and S's, 8-12 in. long.35. 

 OG. Resin-ducts medial. 

 H. Buds oblong-ovate, 

 slightly or not 

 resinous: Ivs. 6-9 

 in. long. 



i. Lvs. light bluish 



Strobus green 33. Txda. 



n. Lvs. dark yellow- 

 green 44. serotina 



HH. Buds ovate, acumi- 



Armandi nate, resinous: Ivs. 



6-11 in. long, dark 



Cembra yellowish green. ... 30. ponderosa 



FF. Length of Ivs. 3-7 in. (see 



also No. 29). 

 G. Character of Ivs. slender. 



Ayacahuite H. Foliage pale yellow- 



ish or bluish green: 

 buds oblong-ovate, 



dark brown 47. attenuata 



Lambertiana HH. Foliage bright green: 



buds ovate, bright 

 chestnut-brown. . . .46. radiata 

 GG. Character of Ivs. stout. 



monticola H. Form of buds thick, 



ovate, acute or 



koraiensis acuminate 30. ponderosa 



[var. scopulorurn 

 HH. Form of buds oblong- 

 ovate 45. rigida 



parviflora AAA. Number of Ivs. 2 (see also No. 14). 



B. Branchlets glaucous. 



flexilis c. Buds very resinous 40. virginiana 



cc. Buds not or little resinous. 



D. Hue of Ivs. dark bluish green. .32. echinata 



Balf ouriana DD% jjue of Ivs. bright green 22. densiflora 



BB. Branchlets not glaucous. 

 anstata c> L eng th of Ivs. 1-3% in. 



D. Branchlets brown or orange: 

 Torreyana resin-ducts medial. 



E. Character of Ivs. slender: 



branchlets brown 39. clausa 



monophylla EE. Character of Ivs. stout, 



Parryana twisted: branchlets orange 



or orange-brown 

 F. Lvs. 1-3% in. long. 



G. Resin-ducts Ior2 42. contorts 



GG. Resin-ducts 2-5 38. pungens 



FF. Lvs. %-l in. long 41. Banksiana 



cembroides DD. Branchlets dull greenish yel- 



low or greenish brown: 

 edulis resin-ducts external. 



E. Character of Ivs. slender: 



Bungeana buds not resinous 36. halepensis 



EE. Character of Ivs. stout: buds 

 coated with resin. 



F. Generally a tree 25. sylvestris 



FF. Generally a shrub 26. montana 



cc. Length of Ivs. 3-9 in. 



D. Color of buds whitish or gray- 



Sabiniana ish white 28. Thunbergii 



DD. Color of buds brown (see also 



No. 36). 



E. Scales of the oblong buds 



Coulter! with reflexed tips, chestnut- 



brown. 



F. Position of resin-ducts 

 Jeffrey! external. 



G. Habit of Ivs. very slen- 

 der and thin 23. Massoniana 



GG. Habit of Ivs. stiff and 



rigid 19. Pinea 



palustris FF. Position of resin-ducts 



medial or internal. 

 G. Buds not resinous: Ivs. 

 canariensis lustrous green, 69 



in. long 37. Pinaster 



GG. Buds resinous: Ivs. 

 longifolia dark green, ^-6 in. 



long 43. muricata 



EE. Scales not reflexed. 



F. Resin-ducts external: Ivs. 

 lustrous: buds ovate, 

 acuminate, resinous. . . . 24. resinosa 

 FF. Resin-ducts medial: Ivs^. 



caribaea dull: buds ovate, acumi- 

 nate, resinous 27. nigra 



FFF. Resin-ducts medial and 

 external: buds oblong- 

 ovate, not resinous: Ivs. 

 sometimes 3 29. sinensis 



