ab 2 C 3 de 2 KEY, BASED UPON LEAVES. 13 



f 2 2^2-4 in. long, with rhomboidal, flexuose scales, narrow erose-dentate and 



elongated at apex BLUE SPRUCE ( P. Parryana } . 



d 2 Leaves in fascicles, 



e Evergreen, quite stiff and in fascicles of 



f 2 each, a membranaceous sheath inclosing the base of each fascicle, about 



g 1 in. long, sheaths very short JACK PINE (P. divaricata) . 



g- l l /2-Zy2 in. long; sheaths % in. or less; branchlets smooth and purple. 



JERSEY PINE (P. Virginiana) . 

 gs 3-5 in. long; branchlets rough. 



h Cones iy 2 -2 in., narrow ovoid, scales armed with weak prickles. 



YELLOW PINE (P. echinata) . 



li 2 Cones 3-4 in., broad-ovoid, scales armed with very thick stout prickles. 



TABLE-MOUNTAIN PINE (P. pungens] . 

 g* 5-6 in. long, thick and with smooth-bossed cones. 



RED PINE ( P. resinosa } . 



f 2 3 each and 3-6 in. long; cones 1^-3 in PITCH PINE (P. rigida). 



g" 5-8 in. long; cones 



h 2-3 in., globular-ovoid, persisting closed on the branches for some years. 



POND PINE (P. serotina) . 



h 2 3-5 in., narrow-ovoid, opening and discharging its seeds the year of 

 maturity; resin-ducts in leaves near surface. 



LOBLOLLY PINE (P. Taeda) , 



gc 8-15 in., resin-ducts not near surface; cones cylindrical-ovoid, 6-10 in. 

 long, breaking away from branch within its b. 



LONG-LEAF PINE (P. palustris). 

 f 3 Both 2 and 3 each ; Rocky Mountain trees. 



ROCK PINE ( P. ponder osa scopulorum ) . 

 f* 5 each, slender, 3-5 in.; cones 4-6 in., curved-cylindrical, with stems. 



WHITE PINE (P. Strobus) . 

 e 2 Deciduous, soft, short and in fascicles of many each (scattered on shoots of 



the season ) TAMARACK ( Larix Americana ) . 



a2 COMPOUND L.EAVKS; 

 b Pinnately compound, 

 c ALTERNATE AND 

 d Entire; 



e Leaflets 3, subsessile, obovate-oblong, remotely crenate-serrate; fr. samara. 



HOP-TREE (Ptelea trifoliata] . 

 e 2 Leaflets 7-9, short-stemmed, ovate to suborbicular and alternately arranged; 



f r. pod YELLOW WOOD ( Cladrastis lutea ) . 



e 3 Leaflets 9-13, short-stemmed, ovate-oblong, abruptly acuminate; fr. shining 



white drupelet POISON SUMACH (Rhus vernix) . 



e 4 Leaflets 11-21, short-stemmed, oblong, obtuse or rounded b., rounded and 

 notched or bristle-tipped a.; fr. pod. 



f Petioles and branchlets glabrous LOCUST (Robinia Pseudacacia) . 



f 2 Petioles and branchlets viscid CLAMY LOCUST (R. viscosa). 



e n 12-25, short-stemmed, lance-falcate; fr. drupe. 



W T ESTERN SOAPBERRY (Sapindus Drummondii). 



d 2 Entire, but remotely serrate toward a.; stem winged between the leaflets; fr. 

 crimson drupelets . DWARF SUMACH (Rhus capallina) . 



