GENERAL KEY TO THE FAMILIES. 



Page. 

 1. Leaves narrow, needle-like, awl like, or scale-like, usually persistent except in the 



genus Larix Pinaceae $7 



1. Leaves broad, flat, rarely five times as long as wide, usually deciduous 2 



2. Leaves opposite or whorled, i. e., two or three occur at a node, 8 



2. Leaves alternate, i. e., only one occurs at a node 10 



3. Leaves, or at least most of them, three at a node, Bignoniaceae 211 



3. Leaves always two at a node, 4 



4. Leaves simple, 5 



4. Leaves compound 8 



5. Leaves palmately lobed Aceraoeae 190 



5. Leaves not lobed, 6 



6. Leaves serrate, Viburnum in Caprifoliaceae 218 



6. Leaves entire, 7 



7. Leaves 3-6 inches long with curving parallel veins; bases of leaf stalks enlarged, 



encircling twigs Cornus in Cornaceae 204 



7. Leaves 4-8 inches long without curving parallel veins; bases of leaf stalks do not en- 



circle twigs, Chionanthus in Oleaceae 217 



8. Leaves palmately compound Sapindaceae 200 



8. Leaves pinnately compound, 9 



9. Leaflets usually 5-11; finely toothed or entire margined Fraxinna in Oleaceae 212 



9. Leaflets usually 3, sometimes 5-lobed or coarsely serrate, ..Acer Negundo in Aceraceae 197 



10. Leaves simple 11 



10. Leaves compound, 40 



11. Leaves persistent, 12 



11. Leaves deciduous 14 



12. Leaves not armed with spiny teeth 18 



12. Leaves armed with spiny teeth, Ilex opaoa in Aquifoliaoeae 181 



13. Small trees; leaves stout, white silky beneath, not taper pointed; flowers soli- 



tary, Magnolia virginiana in Magnoliaoeaa 156 



13. Shrubs; leaves leathery, yellowish-green to scurfy beneath, often taper pointed; 



flowers in clusters Rhododendron and Kalmia in Ericaceae 207 



14. Leaves with entire margins, 15 



14. Leaves with toothed, lobed, or incised margins, 23 



15. Leaves broadly heart-shaped; flowers reddish-purple, shaped like pea blossoms; fruit 



a pea-like pod, Cercis in Leguminosae 180 



15. Leaves not broadly heart-shaped; flowers not shaped like pea blossoms; fruit not 



a pea-like pod, 16 



16. Stout axillary spines present; fruit 3-5 inches in diameter, Maclura in Tlrticaceae 153 



16. Stout axillary spines absent; fruit smaller 17 



17. Leaves decidedly aromatic, often somewhat lobed; twigs spicy-aromatic, mucilagin- 



ous if chewed, Lauraceae 161 



17. Leaves not aromatic or lobed; twigs not spicy-aromatic, nor mucilaginous, 18 



18. Leaves 2-6 inches long; flowers small except pistillate of Diospyros, not soli- 



tary 19 



18. Leaves more than 6 inches long; flowers large and solitary 22 



18. Leaves bristle-tipped, linear-lanceolate to oblong; pith star-shaped; fruit an acorn.... 



Quercus imbrioaria and Q. phellos in Fagaceae 146 



19. Leaves oval-ovate or obovate, not bristle-tipped; pith not star-shaped; fruit a drupe 



or a berry 20 



