ENUMERATION OF CONIFERS 299 



EE. Leaves in clusters of 3: cone prickly. 



F. Cone symmetrical 44. P. rigida 



FF. Cone unsymmetrical. 



G. Prickles of cone minute: upper part of trunk 



rough 45. P. radiata 



GG. Prickles of cone stout: upper part of trimk 



smooth 46. P. attenuata 



CC. Wing of seed thick: leaves 3-5, 6-13 inches long: cones 

 large. 

 D. Leaves in clusters of 3, 6-12 inches long. 



E. Cone conic-oblong; wing of seeds about 1 inch long: 



leaves stout 47. P. Coulteri 



EE. Cone broad-ovoid; wing about half as long as seed: 



leaves slender 48. P. Sabiniana 



DD. Leaves in clusters of 5, rigid, 8-13 inches long: cone 



broad-ovoid; seed short- winged 49. P. Torreyana 



KEY FOR THE DETERMINATION OF PINES WITHOUT CONES 



Bracts subtending the leaf-clusters not decurrent; sheaths of 



leaf-clusters deciduous, sometimes tardily so. 

 B. Leaves in clusters of 5, only occasionally 3 or 4. 

 c. Margin of leaves serrulate. 



D. Young branchlets glabrous or minutely puberulous at 

 first. 

 E. Length of leaves 6-8 inches, slender and pendulous: 



young branchlets glaucous 10. P. excelsa 



EE. Length of leaves 3-5 inches: branchlets not glaucous. 

 F. Branchlets glabrous even when young. 



G. Winter-buds ovoid: leaves more or less ap- 

 pressed to the branch, with marginal resin- 

 ducts 9. P. Pence 



GG. Winter-buds cylindric, chestnut-brown: leaves 



spreading; resin-ducts marginal or medial. 5. P. Armandi 

 FF. Branchlets puberulous at first, soon glabrous: 



spreading 12. P. Strobus 



DD. Young branchlets tomentose or pubescent (sometimes 

 nearly glabrous in No. 6). 

 E. Stomata lacking on back of leaves. 



F. Branchlets pubescent (sometimes nearly glabrous 

 in No. 6). 



G. Length of leaves 4-6 inches, slender 6. P. Ayacahuite 



GG. Length of leaves shorter. 



H. Barkof trunk fissured: leaves 2-4 incheslong.il. P. monticola 

 HH. Bark of trunk smooth: leaves 5-^-2, rarely 

 3 inches long, usually twisted and forming 



brush-tufts at end of branchlets 8. P. parmflora 



FF. Branchlets tomentose. 



G. Habit loose, with spreading branches: leaves 



3-6 inches long 1. P. koraiensis 



GG. Habit compact; branches ascending: leaves 



2-4 inches long 2. P. Cembra 



