1 KEY, BASED UPON FLOWERS. 



a 2 . Gymnospermae seeds naked, borne superficially on carpellary scales. Cone- 

 bearing (Conifer at). 

 b. Scales of cone many, each in the axil of a bract and bearing 2 inverted ovules; 



seeds winged. 

 C. Leaves evergreen, fascicled; cones maturing the second year (Pinus). 



(I. Leaves in 2s with long sheaths; cones about half as long as the leaves 

 and with scales thickened at the end and unarmed. . . .19. P. RESINOSA. 



Armed with a small weak prickle 75. P. MITIS-. 



C? 2 . 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 refiexed spine. 



49. P. RIGIDA. 

 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, cylindrical, large (3-4 in.) and with conspicuous bracts; leaves 



flat, linear 22. A. BALSAMEA. 



(P. Cones pendant and bracts inconspicuous. 



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



21. A. CANADENSIS. 



e 2 . Larger, 1-1^ in., scales eroded at tip; leaves 4-aiigled 20. A. NIGRA. 



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. 



b~. 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. OCCIDENT ALIS. 



Pelteta, 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. 



