KEY, BASED UPON FLOWERS. 



e 3 . Armed with a prickle ; leaves 



3-5 in. long, sheaths elongated 75. P. MITIS. 



14-24 in. long, sheaths short 98. P. IXOPS. 



d?. Leaves in 3s with short sheaths ; cone about half as long as the leaves and 

 with scales thickened at the apex and armed with a reflexed spine. 



49. P. KIGIDA. 

 d?. Leaves in 5s with very short sheaths ; cones longer than the leaves and 



with scales not thickened at the ends, unarmed 50. P. STROBUS. 



C 2 . Leaves evergreen, scattered (not fascicled) ; cones with thin scales, maturing 



the first year (Abies'). 

 d. Cones erect, cyclindrical, large (3-4 in.); leaves 



flat, linear 22. A. BALSAMEA. 



d?. Cones pendant and bracts inconspicuous. 



e. Small, 8 lines or less, scales entire at tip, leaves linear. 



21. A. CANADENSIS. 

 e 2 . Larger ; leaves 4-angled (Picea). 



1-14 i n - l n g scales eroded at tip ; branchlets pubescent. 



20 PICEA NIGRA.* 



2-in. long, subeiitire at tip, branchlets smooth 100. P. ALBA. 



c 3 . Leaves deciduous, soft, needle-shaped and in fascicles of many each. ; cones 

 about 8 lines in length, scales thin (Larix) and with inflected margins. 



23. L. AMERICANA. 



2 . Scales of cone few, without bracts and each bearing 2-8 erect ovules. 

 c. Flowers monoecious ; scales of cone. 



Imbricated and 8-12 in number (Thuja} 24. T. OCCIDENTALS. 



Peltate, with edges joined and about 6 in number (Chamaecyparis). 



74. C. THYOIDES. 



c 2 . Flowers dioecious ; scales fleshy and consolidated, making a small, dark blue 

 berry-like fruit ; leaves scale-like and imbricated in 4 rows. 



25. JUNIPERUS VlRGINIANA. 

 * Given in text as Abies nigra. 



