18 KEY, BASED UPON FRUIT. 



Subovoid, flattened, 1-3 together, involucral spines very sharp 



and hard 40. CASTANEA VESCA. 



e*. Irregularly ; spines many-branched ; nut maturing the second year. 



139. CASTANOPSIS CHRYSOPHYLLA. 

 c 9 . Small, ovoid -lanceolate pods arranged in catkins, opening by two valves 



and containing numerous seeds furnished with silky down ; leaves 

 d. Orbicular-ovate ; petioles flattened ; leaves 



Coarsely dentate 18. POPULUS GRANDIDENTATA. 



Serrate, sharply pointed 72. P. TREMULOIDES. 



Sinuate- toothed, tomentose beneath 96. P. ALBA. 



Obscurely-serrate, with obtuse or rounded apex. 



97. P. HETEROPHYLLA. 



d?. Ovate, closely serrate, whitish and reticulate-veined beneath. 



47. P. BALSAMIFERA. 



ff 3 . Deltoid-ovate 48. P. MONILIFERA. 



d 4 . Broadly deltoid 73. P. DILATATA. 



d*. Linear- lanceolate, tomentose on midrib above and petiole. 



45. SALIX NIGRA. 

 d 6 . Lanceolate or elliptic -lanceolate, smooth above ; capsules ^ 



e. Sessile or nearly so 46. SALIX ALBA var. viTELLiNJf 



e 2 . With slender pedicels ; leaves 



2-4 in. long .71. SALIX AMYGDALOIDES. 



3-7 in. long 140. SALIX LAEVIGATA. 



cf. Oblanceolate or oblong-lanceolate 165. SALIX LASIOLEPIS. 



C 3 . Linear corn pressed pods opening by two valves; pods 



4-5 in. long, k in. broad, quite straight 80. ROBINIA PSEUD ACACIA. 



2 in. long, in. broad, often curved into a circle. 



155. ACACIA MELANOXYLON. 

 C 4 . Subcylindrical pods, long, opening by two valves. 



6-10 in. long, i/i in. or less thick 134. CHILOPSIS SALIGNA. 



10-12 in. or more long, in. or more thick. .89. CATALPA BIGNONIOIDES. 



c 5 . Ovoid 5-valved capsule 102. GORDONIA LASIANTHUS. 



c 6 . Subovoid follicle with seed suspended by funiculi when ripe. 



106. XANTHOXYLUM CLAVA-HERCULIS. 

 c 7 . Three-lobed capsules dividing into three dehiscent cocci. 



151. CEANOTHUS THYRSIFLORUS. 

 a 2 . Aggregated fruit composed of many carpels, either closed or opened and 



cohering or closely massed together, forming a 

 b. Cone. 



c. Scales of the cone open carpels (Coniferce). 

 d. Scales many and spreading at maturity. 



e. Imbricated and each subtended by a bract ; ovules, 2, inverted, and 

 /. Maturing the year after flowering (Pinus) ; cones 

 ff. Subterminal and scales 

 h. Thin at tip and unarmed; cones subcylindric and 



4-6 in. long 49. P. STROBUS, 



12-18 in. long 146. P. LAMBERTIANA. 



W. Thickened at tip and 

 i. Armed with a recurved prickle. 



J. 1-3 in. long, cylindric ovid, oblique 148. P. CONTORTA. 



j*. 3-6 in. long, glossy-brown, separating from the tree by a 

 fracture 



Within the peduncle 125. P. CUBENSIS. 



Within the base of cone 147. P. PONDEROSA. 



j 3 . 6-10. in. long 124. P. PALUSTRIS. 



i 2 . Unarmed cones about 2 in. in length, straight. 



19. P. RESINOSA. 



<jr 2 . Lateral and scales thickened at tip, cones 

 h. Slightly or not at all oblique 



i. Ovoid-oblong: leaves 3-5 in. long; scales armed with a weak 



prickle directed 

 At about right angles from the axis of the closed cone. 



75. P. MITIS. 

 Forward, at about 45 or less from the axis. . 123. P. GLABRA. 



