50 PINACEAE. 



i. PINUS L. Sp. PI. 1000. 1753. 



Evergreen trees with two kinds of leaves, the primary ones linear or scale-like, decidu- 

 ous, the secondary ones forming the- ordinary foliage, narrowly linear, arising from the axils 

 of the former in fascicles of 2-5 (rarely solitary in some western species), subtended by the 

 bud-scales, some of which are united to form a sheath. Staminate aments borne at the 

 bases of shoots of the season, the clusters of stamens spirally arranged, each in the axil of 

 a minute scale ; filaments very short ; anthers 2-celled, the sacs longitudinally dehiscent. 

 Ovule-bearing aments solitary or clustered, borne on the twigs of the preceding season, com- 

 posed of numerous imbricated minute bracts, each with an ovule-bearing scale in its axil, 

 ripening into a large cone, which matures the following autumn, its scales elongating and 

 becoming woody. Seeds 2 on the base of each scale, winged above, the testa crustaceous. 

 [Name Celtic.] 



Leaves 5 in a sheath; cone-scales little thickened at the tip. 

 Leaves 2-3 in a sheath; cone-scales much thickened at the tip. 

 Cones terminal or subterminal. 



Leaves 2 in a sheath; cones i^'-2^' long, their scales pointless. 

 Leaves 3 in a sheath; cones 4'-io' long, their scales prickle-tipped. 

 Cones light, 6'-io' long; leaves 10 -16' long. 

 Cones very heavy and wood}-, 4' -6' long; leaves 5'-io' long. 

 Cones lateral. 



Cone-scales with neither spine nor prickle ; leaves in 2's. 

 Cone-scales tipped with a spine or prickle. 

 Leaves some or all of them in 2's. 



Cones iM'-z'A' long, their scales tipped with prickles. 

 Leaves stout, i l A'-2 l A' long. 



Leaves slender, 3' -5' long. 7. 



Cones 3^'-5' long, their scales tipped with very stout short spines. 



8. 

 Leaves in 3*5 (very rarely some in 2's or 4*3 ). 



Leaves6'-io' long; old.sheaths 6"-io" long; cones oblong-conic. 9. 

 Leaves 3' -5' long; old sheaths 3"-6" long; cones ovoid. 10. 



P. Strobus. 



P. resinosa. 



P. palitsfris. 

 P. ponderosa. 



5. P. divaricata. 



6. 



/'. 



P. echinata. 



P. pungens. 



P. Taeda. 

 P. rigida. 



i. Pinus Strobus L,. White Pine. Weymouth Pine. (Fig. no.) 



Finns Strobus L. Sp. PI. 1001. 1753. 



A large forest tree, reaching a maximum 

 height of 175 and a trunk diameter of io^, 

 the bark nearly smooth except when old, the 

 branches horizontal, verticillate. Leaves 5 

 in a sheath, very slender, pale green and glau- 

 cous, 3 '-5' long, with a single fibro-vascular 

 bundle, the dorsal side devoid of stomata ; sheath 

 loose, deciduous ; ovule-bearing aments ter- 

 minal, peduncled ; cones subterminal, droop- 

 ing, cylindric, often slightly curved, 4 '-6' long, 

 about \' thick when the scales are closed, re- 

 sinous; scales but slightly thickened at the 

 apex, obtuse and rounded or nearly truncate, 

 without a terminal spine or prickle. 



In woods, often forming dense forests, Newfound- 

 land to Manitoba, south along the Alleghenies to 

 Georgia and to Illinois and Iowa. Ascends to 4300 

 ft. in North Carolina and to 2500 ft. in the Adiron- 

 dacks. Wood light brown or nearly white, soft, 

 compact, one of the most valuable of timbers; 

 weight per cubic foot, 24 Ibs. June. 



