XXIV ANALYTICAL KEY TO THE GENERA 



Winter-buds resinous; leaves crenate, usually truncate at base; peti- 

 oles slender. Populus (p. 119). 

 Winter-buds not resinous. 



Leaf-scars with 3 bundle-traces. 



Leaves involute in bud, often lobed on vigorous shoots; winter- 

 buds obtuse, short, pubescent. Malus (p. 379). 

 Leaves conduplicate (or in some species of Prunus convolute), 



never lobed ; winter- buds acute. 

 Winter-buds elongated ; branches never spinescent. 



Amelanchier (p. 393). 



Winter-buds not elongated, ovoid; branches sometimes spi- 

 nescent. Prunus (p. 555). 

 Leaf -scars with 1 bundle-trace; leaves simply serrate. 



Ilex sp. 5-6 (p. 673) . 



Primary veins extending to the teeth or to the lobes. 

 Leaves lobed. Quercus sp. 1-16, 35-50 (pp. 241, 283). 



Leaves serrate-toothed. 



Winter-buds with numerous scales. 



Leaves lustrous beneath, remotely serrate or denticulate; winter- 

 buds elongated, acuminate. Fagus (p. 228) . 

 Leaves pale beneath, coarsely dentate or serrate; winter- buds 

 acute. Chestnut Oaks. Quercus sp. 51-54 (p. 303). 

 Winter-buds with 2 pairs of scales. Castanea (p. 230) . 

 Leaves doubly or simply serrate, or lobed, with serrate lobes; branches 



often furnished with spines. 



Leaves involute in the bud ; branchlets often ending in blunt spines. 



Malus (p. 379) . 



Leaves conduplicate in the bud ; branches usually armed with sharp- 

 pointed single or branched axillary spines. Crataegus (p. 397). 

 bb Stipules wanting. 



c Leaves not lobed. 



Leaves subcoriaceous, oblong, sometimes nearly entire, glabrous. 



Symplocos (p. 831). 

 Leaves thin. 



Leaves oblong-obovate, acute, pubescent beneath. 



Gordonia alatamaha (p. 752). 



Leaves oblong or lanceolate, acuminate, glabrous or puberulous while 



young, turning scarlet in the autumn. Oxydendrum (p. 796). 



Leaves ovate to elliptic, stellate-pubescent or glabrous, turning yellow in 



the autumn. Halesia (p. 824). 



cc Leaves palmately lobed. 



Stipules large, foliaceous, united ; branchlets without a terminal bud. 



Platanus (p. 371). 

 Stipules small, free, caducous; branchlets with a terminal bud. 



Liquidambar (p. 367). 



tf Leaves inconspicuous or wanting; branches spiny or prickly. 



Branches or stems succulent, armed with numerous prickles. 



Branches and stems columnar, ribbed, continuous; leaves 0. Cereus (p. 757). 

 Branches jointed, tuberculate; leaves scale-like. Opuntia (p. 759). 



Branches rigid, spinescent. 



Leaves minute, narrow-obovate. 



Branchlets bright green. Koeberlinia (p. 754). 



Branchlets red-brown. Dalea (p. 621). 



Leaves scale-like, caducous. Canotia (p. 677). 



2. LEAVES COMPOUND. 

 * Leaves 3-foliolate, without stipules. 



Leaves persistent; leaflets obovate, entire, sessile. Hypelate (p. 716)_ 



Leaves deciduous. 



