.98] CLASSIFICATION AND DESCRIPTION 171 



GENUS 93. PtNUS. (THE PINES.) 



Leaves needle-shaped, 1 to 15 in. long, almost cylindric, 

 2, 3, or 5 together in clusters, with a sheath, more or 

 less persistent, at the base. Flowers monoecious, both 

 staminate and pistillate in catkins, usually insignificant 

 and uunoticeable. In spring. Fruit a cone, persistent 

 and formed of more or less woody, overlapping scales. 



* Leaves usually 5 together in bundles. (A.) 



A. Leaves 6 in. or more long, glaucous green and very pendu- 

 lous 1. 



A. Leaves under 4 in. long. (B.) 



B. Cones over 10 in. long, on stalks 3 in. long, pendulous when 



ripe 2. 



B. Cones 4 to 10 in. long. (C. ) 



C. Scales of cones thin, unarmed 3, 4. 



C. Scales of cones thick and woody, obtuse, 1 in. broad 



5. 



B. Cones under 4 in. long; scales slightly hooked but point- 

 less , 6. 



* Leaves usually in threes, rarely in twos; scales of cones with 



spines or prickles. (D.) 

 D. Scales of cones with short, rigid, straight spines; leaves 6 to 



10 in. long 7. 



D. Scales with sharp, bent prickles. (E.) 



E. Leaves over 5 in. long, sometimes 15 in. long 8, 9. 



E. Leaves 3 to 5 in. long, rigid and flattened, from short 

 sheaths 10. 



* Leaves usually in twos; cones rarely over 3 in. long. (F.) 

 F. Leaves over 3 in. long. (G-. ) 



G. Cone-scales with dull spines 11. 



G. With small or minute, persistent prickles 12, 13, 14. 



G. With no prickles, or small ones, early deciduous ... 15, 16. 

 F. Leaves 3 in. or less long. (H.) 

 H. Cone-scales with straight or slightly curved, rigid spines 



17. 



H. Cone-scales with stout, recurved spines 18, 19. 



H. Cone-scales with small prickles which are early deciduous 



20. 



H. Cone-scales without spines or prickles 21, 22. 



