PINACEAE. 



1. PINUS L. Pine. 



Evergreen trees with 2 kinds of leaves, the primary 

 ones Hnear or scale-like, deciduous; the secondary ones 

 forming the ordinary foliage, narrowly linear, arising 

 from the axils of the former in fascicles of 2-5, or soli- 

 tary in a single species; subtended by the bud scales, 

 some of which are united to form a sheath. Staminate 

 cones borne at the bases of the shoots of the season, the 

 clusters of stamens spirally arranged each in the axil of 

 a minute scale; filaments very short; anthers 2-celled, 

 longitudinally dehiscent. Ovule-bearing cones solitary 

 or clustered, borne on the twigs of the preceding year, 

 composed 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. 



Sheaths of the leaves deciduous; leaves with 1 

 fibro-vascular bundle. 

 Leaves in 5's; cones with terminal unarmed 

 umbos. 

 Cones 3-5 dm. long; seeds much shorter 

 than the wings, these not persistent on 

 the scale. 1. P. lambertiana. 



Cones about 1 dm. long; seeds much 

 longer than the wings, these persistent 

 on the scale. 2. P.flexilis. 



Leaves in 1-4-leaved clusters; cones sub- 

 globose; scales few, much thickened; 

 seeds large; wings a mere ring. 

 Leaves usually in 4's. 3. P. quadrifolia. 



Leaves solitary. 4. P. monophylla. 



Sheaths of the leaves persistent; leaves with 2 

 fibro-vascular bundles. 

 Leaves in 5's. 5. P. torreyana. 



Leaves in 2-3-leaved clusters. 

 Leaves in 3's. 



Cone scales with dorsal slender 

 prickles. 

 Cones symmetrical, opening at 

 maturity, deciduous, the 

 basal scales persistent on 

 the branches. 

 Leaves yellow green; twigs not 

 glaucous; cones 7-15 cm. 

 long. 6. P. ponderosa. 



