April, 1912.] Key to the Fruits of the Genera of Trees. 509 
35. Seed without wings or hairs. 39. 
36. Seed with a tuft of hairs, capsule small. 37. 
36. Seed with wings, the wings sometimes with a fringe of 
long hairs. 38. 
37. Capsule with a little cup at the base. Populus. 
37. No cup at the base of the capsule but 1 or 2 little glands 
may be present. Salix. 
38. Capsule very long, wings of seed with a fringe of hairs. 
Catalpa. 
38. Capsule short, wing of seed without hairs. Paulownia. 
39. Seeds very large, }/2~2 in. in diameter. 40. 
39. Seeds much less than 3^ in. in diameter. 41. 
40. Seed smooth with a large light spot at one end, without 
ridges or angles. Aesculus. 
40. Seed with two or more vertical ridges, without a special light 
spot — a nut in an enclosing husk which may be mistaken 
for a capsule. Hicoria. 
41. Seeds with a fleshy, scarlet aril, capsule lobed. Euonymus. 
41. Seeds without an aril. 42. 
42. Seeds 1 or 2, capsule not bladdery. 43. 
42. Seeds several to many. 44. 
43. Capsules small without a cup at the base. Xanthoxylum. 
43. Capsule woody, x /i in. long, with a prominent cup at the 
base; seeds 2, oblong. Hamamelis. 
44. Capsule triocular, large, bladdery. 45. 
44. Capsule with 5 — many cavities, small. 46. 
45. Capsule 3-lobed at the tip, with 3 styles, usually widest at 
the middle or toward the outer end. Staphylea. 
45. Capsule with a long, acute tip, with a single style, widest 
below the middle. Koelreuteria. 
46. Capsules mostly woody, oblong, puberulent; in corymbose 
or umbellate clusters. Rhododendron. 
46. Capsules depressed-globose, somewhat 5-lobed; in corymbose 
or umbellate clusters. Kalmia. 
46. Capsules ovoid-pyramidal, 5-angled; in large panicled 
racemes. Oxydendrum. 
47. Fruit a dry drupe, or drupe-like; exocarp softer than the bony 
endocarp. 48. 
47. Fruit a nut or achene, the pericarp not in 2 layers; often 
partly or completely enclosed in a cup or husk. 49. 
48. Fruit globose, in. or more in diameter, on winged peduncles 
Tilia. 
4S. Fruit obliquely ovoid, compressed, ridged on the back and 
covered with prominent soft processes. Planera. 
48. Fruit subglobose, nearly symmetrical, f in. long, pubescent 
or if not the stone striate. Rhus. 
