KEY, BASED UPON FRUIT. 13 



d. Coriaceous or woody, dehiscent by 



e. 2-3 valves and containing one or very few large seeds with smooth shining 

 coat and a large scar (sEsculus), fruit 



Prickly and leaflets 7 ' 6 ^ESCULUS HIPPOCASTANUM. 



Smooth and leaflets 5 127. ^EscuLus CALIFORNICA. 



e 9 . 4 more or less distinct valves (Carya). 

 /'. Epicarp thick and separating quite freely to the base ; nut ridged, with 



thick shell, globular-ovoid and 

 g. Flattened, 



1 in. or less in length 36. CARYA ALBA. 



H in. or more in length 64. CARYA SULCATA. 



gr*. Not so much flattened, usually 4-angled 90. CARYA TOMENTOSA. 



f j . Epicarp only moderately thick and nut of medium size, moderately 



ridged and with shell of medium thickness 65. CARYA PORCINA. 



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

 g. Astringent and bitter ; sutures of epicarp very p'rominent ; nut 

 Quite smooth, whitish and only slighly compressed. 



37. CARYA AMARA. 

 Rough, reddish, strongly compressed and angled. 



115. CARYA AQUATICA. 

 g*. Slightly if at all bitter, nut whitish and sutures moderately prominent. 



91. CARYA MICROCARPA. 

 e 3 . 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" 2 . Irregularly ; spines many-branched ; nut maturing the second year. 



1K9. CASTANOPSIS CHRYSOPHYLLA. 



e 3 . Into three cocci, each liberating a single seed 189. RICINUS COMMUMS. 



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



and containing numerous seeds furnished with silky down ; capsule 

 d. Oblong-conical, small and thin- walled ; leaves 

 e. Orbicular-ovate and 



/. Coarsely dentate 18. POPULUS GRANDIDENTATA. 



/*. Serrate, short- pointed 72. POPULUS TREMULOIDES. 



Sinuate, wooly tomentose beneath 96. POPULUS ALBA. 



Linear lanceolate, tomentose on midrib above and petiole. 



45. SALIX XIGKA. 



e 9 . Ovoid-oblong, larger and thicker walled: leaves 

 f. Broad-ovate, obscurely crenate-serrate obtuse or rounded at apex. 



97. POPULUS HETEROPHYLLA. 



f 1 . Ovate or ovate-lanceolate, acuminate, whitish and reticulate-veined 



beneath 47. P. BALSAMIFERA. 



/X Deltoid ovate coarsely crenate-serrate usually. 



Abruptly acuminate 48. POPULUS MONILIFERA. 



Shorter pointed or acute 194. POPULUS FREMONTII. 



/*. Broadly deltoid 63, POPULUS DILATATA. 



f/ 2 . Larger, subglobose and pubescent 218. POPULUS TRICHOCARPA. 



d 6 . Lanceolate or elliptic lanceolate, 

 e. 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. 



c s . Pubescent; capsules about 



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



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



c ? . Linear compressed pods opening by two valves; pods 



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



3-5 in. long, variously twisted 206 ACACIA DECURRENS. 



