KEY, BASED UPON LEAVES. 7 



e 3 . Leaflets 3-5, prominently veined, irregularly toothed. 



54. ACER NEGUNDO. 

 d*. Sessile or subsessile 



e. Numerous (15-17) and pubescent, especially along the petioles and rachis. 

 /". Leaflets ovate-lanceolate, finely serrate; pubescence of short, rust-colored, 

 clammy hairs. 



Fruit subovoid, viscid-pubescent 14. JUGLANS CINEREA. 



Fruit globose, roughly dotted (not viscid-pubescent). 



35. JUGLANS NIGRA. 

 / 2 . Leaflets lance-oblong, coarsely serrate; pubescence of copious, longer 



and white hairs 5. RHUS TYPHINA. 



e 9 . Fewer, (5-11). 



5, quite glabrous; fruit a ridged nut about 1 in. long with thick 



epicarp 36. GARY A ALBA. 



7-9, finely pubescent; nut ridged and larger 64. C. SULCATA. 



5-7, glabrous, obovate; nut quite smooth 65. C. PORCINA. 



7-11, lanceolate, acute at base, minutely glandular and pubescent 



beneath 37. C. AMAR A. 



Oblong-lanceolate, glabrous, obtuse or rounded at base; fruit a 



samara, flat at base 62. FRAXINUS SAMBUCIFOLIA. 



b s Decompound Leaves. 



C. Petioles smooth and leaves 



Regularly bipinnate excepting for the lowest pair of single leaflets; 



leaflets stalked 27. GYMNOCLADUS CANADENSIS. 



Irregularly bipinnate, leaflets small and sessile. 



28. GLEDITSCHIA TRIACANTHOS. 

 c 2 . Petioles prickly, leaves large with ovate, sessile, serrate leaflets. 



8. ARALIA SPINOSA. 



tt 2 . Leaves Evergreen remaining on over winter. 

 ft. Needle-shaped and quite stiff, pointing every way. 

 C. Long, 1 in. or more, in fascicles of 



d. Two each, a broad membranous sheath inclosing the base of each fascicle. 

 Leaves slender, 3-5 in. long; scales of cone armed with a weak prickle. 



75. PINUS MITIS. 

 Leaves thicker, 5-6 in. long; scales thickened but unarmed. 



19. PINUS RESINOSA. 



d 2 . Three each, sheath short 56. PINUS RIGIDA. 



d 3 . Five each, sheath deciduous 49. PINUS STROBUS. 



C 2 . Short, 8 lines or less, scattered (not in fascicles), 4-angled, usually more or 



less curved .20. ABIES NIGRA. 



6 2 . Linear, small, flat and diverging in two directions. 



c. Petioled, obscurely denticulate, 8 lines or less in length. 



21 . ABIES CANADENSIS. 



c 2 . Sessile, entire, 8 lines or more in length 22. ABIES BALSAMEA. 



b :i . Scale-like or awl-shaped. 



c. Imbricated and closely appressed in four ranks, but making a conspicuously 



flat and two-edged branchlet 24. THUJA OCCIDENTALIS. 



c-. Scale-like, smaller, appressed in four ranks and making a rather 4-angled 

 than flat branchlet; fruit a 



Small spherical cone 74. CHAMAECYPARIS TKYOIDES. 



Bluish berry 25 . JUNIPERUS VIRGINIANA. 



