PINACE.E 11 



of southern California where it is common on the San Beruadino and San Jacinto Moun- 

 tains between altitudes of 3500 and 7000, and on the Sierra del Final, Lower California; 

 often forming extensive open forests at elevations between 5000 and 7000. 



PITCH PINES. 



Wood usually heavy, coarse-grained, generally dark-colored, with pale often thick sap- 

 wood; cones green at maturity (sometimes purple in 10 and 21) becoming various shades of 

 brown; cone-scales more or less thickened, mostly armed; seeds shorter than their wings 

 (except in 17 and 28) ; leaves with 2 fibro- vascular bundles. 



Sheaths of the leaf-clusters deciduous; cones |'-2' long, maturing in the third year, leaves 

 in 3-leaved clusters, slender, 2|'-4' long. 9. P. leiophylla (H). 



Sheaths of the leaf-clusters persistent. 



Leaves in 3-leaved clusters (3 and 5-leaved in 10, 3-2 leaved in 12). 



Cones subterminal, usually deciduous above the basal scales persistent on the branch. 

 Buds brown; leaves in 2-5-leaved clusters. 10. P. ponderosa (B,F,G,H). 



Buds white. 11. P. palustris (C). 



Cones lateral. 



Cones symmetrical, their outer scales not excessively developed. 

 Leaves in 2 and 3-leaved clusters, 8'-12' long; cones short-stalked. 



12. P. caribaea (C). 

 Leaves in 3-leaved clusters; cones sessile. 



Cones oblong-conic, prickles stout; leaves 6'-9' long. 13. P. taeda (A, C). 



Cones ovoid, prickles slender; leaves 3'-5' long. 14. P. rigida (A, C). 



Cones unsymmetrical by the excessive development of the scales on the outer side. 



Cones 5 '-6' long, their scales not prolonged into stout, straight or curved spines. 



Prickles of the cone-scales minute. 15. P. radiata (G). 



Prickles of the cone-scales stout. 16. P. attenuata (G). 



Cones 6'-14' long, their scales prolonged into stout, straight or curved spines; 



leaves long and stout. 



Cones oblong-ovoid; seeds longer than their wings. 17. P. Sabiniana (G). 



Cones oblong-conic; seeds shorter than their wings. 18. P. Coulteri (G). 



Leaves in 2-leaved clusters (2 and 3-leaved in 23). 

 Cones subterminal. 



Cones symmetrical, 2'-2|' long, their scales unarmed; leaves 5 '-6' long. 



19. P. resinosa (A). 



Cones unsymmetrical by the greater development of the scales on the outer side, 

 armed with slender prickles; leaves l'-4' long. 20. P. contorta (B, F, G). 



Cones lateral. 



Cones about 2' long. 



Cone-scales very unevenly developed and mostly unarmed; cones incurved; leaves 

 less than 2' long. 21. P. Banksiana (A). 



Cone-scales evenly developed, armed with weak or deciduous prickles; leaves up 

 to 4' in length. 



Bark of the branches and upper trunk smooth. 22. P. glabra (C). 



Bark of the branches and upper trunk roughened. 23. P. echinata (A, C). 

 Cones about 3' long, armed with persistent spines. 

 Cone-scales armed with slender or stout prickles. 



Cone-scales evenly developed, their prickles slender, acuminate, from a broad 



base; leaves 3' long or less. 



Cones opening at maturity. 24. P. virginiana (A, C). 



Cones often remaining closed for many years. 25. P. clausa (C). 



Cone-scales unevenly developed and armed with stout prickles; cones 2'- 3^' 



long, remaining closed; leaves 4'-6' long. 26. P. muricata. 



