ENUMERATION OF CONIFERS 297 



FF. Cone 3J^-10 inches long, cylindric: branchlets 

 glabrous. 



G. Leaves 3-4 inches long, stiff 9. P. Pence 



GG. Leaves 6-8 inches long, drooping 10. P. excelsa 



EE. Cone-scales uniformly thin. 



F. Branchlets pubescent at first: leaves stiff 11. P. monticola 



FF. Branchlets glabrous or slightly puberulous: leaves 



thin, soft ' 12. P. Strobus 



BB. Scales with dorsal umbo. 



c. Seeds wingless or with very short wing: cones green at 

 maturity. 



D. Leaves entire, ?4-l ' j inches long, 1— i in a fascicle 13. P. cembroides 



DD. Leaves .serrulate, 2-4 inches long, 3 in a fascicle 14. P. Bungeana 



cc. Seeds with long wing; cones purple at maturity. 



D. Cones with minute incurved prickles 15. P. Balfouriana 



DD. Cones with long and slentler prickles 16. P. aristata 



AA. Bracts subtending the leaf-fascicle dccurrent; sheath persis- 

 tent; leaves with two fil>ro-vascular bundles: umbo of cone- 

 scales dorsal (Diploxylox). 

 B. Seed-wing very short or long and adnate. 



c. Wing long, adnate: leaves 8-12 inches long, in clusters of 3. 

 D. Apophysis elongated and recurved; seed ^-l^ inch 



long: stem and branches without small branchlets. . . 17. P. longifolia 

 DD. Apophysis broad-pyramidal; seed } 2 inch long: stem 



and branches with small branchlets 18. P. canariensis 



cc. Wing very short, deciduous: leaves 5-8 inches long, 2 19. P. Pinea 



BB. Seed-wing articulate (detachable as a whole). 

 c. Wing of seed membranous, long. 



D. Cones deciduous, dehiscent at maturity (in No. 26 

 persistent and leaves sometimes 3). 

 E. Leaves in clusters of 2: spring-shoots uninodal and 

 cones subterminal. 

 F. Bark of 2-4-year-old branchlets without sharply 

 defined conspicuous oblong scales, peeling off ir- 

 regularly: leaves with marginal resin-ducts. 

 G. Branchlets bloomy: leaves 2^^-5 inches long. . .20. P. densiflora 

 GG. Branchlets not bloomy. 



H. Length of leaves 4-8 inches 21. P. Massoniana 



HH. Length of leaves ^4-3 inches. 



I. Cone short-stalked, with an obtuse gray 

 imibo: leaves more or less bluish-green: 



usually a tree 23. P. sylvestris 



n. Cone subsessile, with prickly umbo: leaves 



bright green: usually a shrub 24. P, Mugo 



FF. Bark of 2-4-year-old branchlets covered with 

 conspicuous sharply defined scales (the decur- 

 rent base of the bract), each peeling off as a 

 whole: leaves 23^7 inches long. 



G. Branchlets grayish-white 25. P. leucodermis 



GG. Branchlets grayish-yellow or orange to brown. 

 H. Resin-ducts of leaves medial or medial and 

 marginal. 



