KEY TO THE GENERA OP TREES 57 



i. Large tree, with fruit 1 in. in diameter, dry, rough, hanging 



on a long stem " 41. Liquidambar. 



i. Small tree with few branches and the trunk usually quite 



prickly ; fruit berry-like in large clusters 44. Aralia. 



j. Fruit small berries, with 3 flattened seeds, in clusters in the axils 



of the leaves, which are decidedly 3-ribbed from the base 



'. 21. Hovenia. 



j. Fruit small drupes, with 1 seed, either solitary or in pairs in 

 the axils of the leaves, (k.) 



k. Plant without prickles; leaves decidedly oblique at base 



76. Celtis. 



k. Plant with prickles ; leaves narrow, decidedly 3-ribbed, and 



2-ranked on green twigs 22. Zizyphm. 



1. Fruit not very edible ; leaves rough above, very hairy below, on 



some of the twigs opposite 79. Broussonetia. 



1. Fruit edible; leaves not very hairy, never opposite. .78. Morus. 



m. Leaves of 3 entire-edged leaflets ; fruit a pea-like pod 



28. Laburnum. 



m. Leaves of 3 quite regularly serrate, transparent-dotted 



leaflets 13. Ptelea. 



m. Leaves once or twice pinnate ; the leaflets entire, (s. ) 

 m. Leaves once or twice pinnate ; the leaflets with margins more 



or less serrate or notched, (n.) 



n. Leaves irregularly once to twice, in one case three times, pin- 

 nate, (r.) 



n. Leaves regularly once pinnate, (o.) 

 o. Leaves less than 1 ft. long, on a small, quite prickly plant ; 



fruit very small pods (% in. long) 12. Xantlioxylum. 



o. Leaves less than 1 ft. long; leaflets 3 in. or less long; fruit 

 bright-colored, berry -like pomes in clusters, persistent through 

 the autumn ; plant not thorny ; branches not heavy-tipped . 



37. Pyrus. 



o. Leaves usually larger on the small tree or almost a shrub ; 



juice in most cases milky ; branches heavy-tipped . 27. Rims. 



o. Leaves 1-2 ft. long; leaflets 3 in. or more long; fruit a bony 



nut with green fleshy coat; large trees, (q.) 

 o. Leaves very large, 2 ft. or more long on the rapid-growing 

 branches; branches he a vy -tipped ; odor of bruised leaves 

 quite strong; leaflets 15 or more in number; large trees; 

 juice not milky, (p. ) 



p. Leaflets with 1-3 glandular notches at the base 



17. Ailanthus. 



p. Leaflets entire at base, but very slightly sen-ate near the tip 

 18. Cedrcla. 



