2u KEY, BASED UPON FRUIT. 



/ 3 . Epicarp tliin, nuts small and thin-shelled ; kernel 

 </. Astringent and bitter ; sutures of epicarp very prominent ; nut 

 Quite smooth, whitish and only slighly compressed. 



37. CARYA AMARA. 

 Rough, reddish, strongly compressed and angled. 



115. CARYA AQUATICA. 

 </ 2 . Slightly if at all bitter, nut whitish and sutures moderately prominent. 



91. CARYA MICROCARPA. 

 e 5 . 5-20 valves recurving from central axis and liberating numerous fine 



seeds 158. RHODODENDRON CALIFORNICUM. 



d-. Covered with spines ; dehiscent 

 e. By four valves ; nuts 



Sharply 3- angled, 2 together, involucre soft-prickly. 



16. 'FAGUS FERRUGINEA- 



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. 



e". Into three cocci, each liberating a single seed . . . .189. RICINUS COMMUNIS. 

 c' 2 . Small, ovoid-lanceolate pods arranged in catkins, opening by two valves 



and containing numerous seeds furnished with silky down ; leaves 

 d. Orbicular-ovate ; petioles laterally compressed; 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. 



d 3 . Deltoid-ovate, coarsely crenate-serrate, usually 



Abruptly acuminate 48. P. MONILIFERA. 



Shorter pointed or acute 194 P. FREMONTII. 



d 4 . Broadly deltoid , . 73. P. DILATATA. 



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



45. SALIX NIGRA. 



f/ 6 . Lanceolate or elliptic lanceolate, 

 c. Smooth and capsules 



/ Sessile or nearly so 46. SALIX ALBA var. VITELLINA. 



/-. With slender pedicels ; leaves pale glaucous beneath and 



2-4 in. long 71. SALIX AMYGDALOIDES. 



3-7 in. long 140. SALIX LAEVIGATA. 



e*. Pubescent; capsules about 



in. long, ovate-lanceolate 193. SALIX NUTTALLII. 



i in. long, oblong-ovoid 165. SALIX LASIOLEPSIS. 



<- ?i . Linear com pressed pods opening by two valves; pods 



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



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



155. ACACIA MELANOXYLON. 

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



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



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



r . Ovoid 5-valved capsule 102. GORDOMA LASIANTHUS. 



c' 1 . Subovoid follicles arranged 



In pairs, seed not suspended by a funiculus. 



182. LYONOTHAMNUS FLORIBUNDUS. 

 Not in pairs; seed suspended by a funiculus. 



106. XANTHOXYLUM CLAVA-HERCULIS. 



c 7 . Three-lobed capsules dividing into three dehiscent cocci; (Ceanothus) 

 branchlets 



Conspicuously angled 151. C. THYRSIFLORUS. 



Slightly angled 1 77. C. ARBORKUS. 



c 8 . Top-shaped capsule of 4 or 5 cells dehiscent at their summits. 



183. EUCALYPTUS GLOBULUS. 



