-70 ULMACEAE, 
3. Twigs not corky-winged. 4. 
Twigs often warty or corky-winged. 12. 
4. Buds glabrous. 5. 
Buds pubescent. 9. 
5. Flowers stalked: fruit glabrous except the edge. 6. 
Flowers nearly sessile: fruit pubescent. U. campestris. 
6; Trees.) 7. 
Shrub. U. americana nana. 
7. Leaves green. 8. 
Leaves yellow. U. americana aurea. 
8. Not weeping. (White elm). U. americana. 
Somewhat weeping. U. americana pendula. 
9. Twigs bristly: buds red-hairy. (Slippery elm). U. fulva. 
Twigs and buds soft-pubescent. Io. 
10. Leaves green. II. 
Leaves purple. U. glabra atropurpurea. 
Ir. Not weeping. (Scotch elm). U. glabra. 
Weeping. U. glabra camperdownii. 
12. Flowers slender-stalked. 13. 
Flowers nearly sessile. Forms of U. campestris. 
13. Buds glabrous: corky wings thin. U. alata. 
Buds pubescent: twigs coarsely corky. U. racemosa. 
PLANERA. Planer Tree. 
Deciduous small trees with somewhat brownish wood with 
minute ducts sometimes in evident tangential lines, and fine 
medullary rays; slender terete zig-zag twigs; small rounded con- 
tinuous pith; alternate 2-ranked half-round somewhat raised 
leaf-scars; sessile round-ovoid buds with several 2-ranked 
scales, the end-bud absent; short-petioled sometimes oblique 
rather small and thick toothed leaves; small perfect apetalous 
clustered flowers appearing before the foliage; and small rounded 
blunt-spiny fruit. 
Leaves ovate, unequally biserrate. P. aquatica. 
ZELKOVA, 
Deciduous rather small trees with slender twigs; small pith; 
alternate 2-ranked scarcely raised half-elliptical leaf-scars with 
