THE ELMS AND THE HACKBERRIES - FAMILY ULMACEAE. Genus ULMUS, Linn. Trees of horticultural and lumber value. Leaves alternate serrate, unequal at base, with strong ribs and short petioles Flowers greenish, inconspicuous, perfect. Fruit a dry nutlet with thin encircling wing, bearing two hooks at apex.
KeY TO SPECIES A. Blooming before the leaves in spring.
B. Twigs smooth.
C. Branches corky winged.
(U. alata) WAHOO or WINGED ELM CC. Branches not corky winged.
(U. Americana) AMERICAN or WATER ELM BB. Twigs pubescent.
C. Branches corky. (U. Thomasi) CORK ELM CC. Branches not corky; leaves rough above; twigs and buds with coarse, rusty hairs.
(U. fulva) SLIPPERY ELM AA. Blooming late in summer or autumn.
B. Leaves over 2 inches long, thin. (U. serotina) RED ELM
BB. Leaves 1 to 2 inches long, thick.
(U. crassifolia) CEDAR ELM 2. Genus CELTIS, Linn.
Valuable shade trees. Leaves simple, 3-nerved, serrate. Flowers polygamo-moneecious, axillary, small. Fruit sweet, succulent berry.
A. Leaves coarsely and sharply serrate; fruit large.
(C. occidentalis) HACKBERRY AA. Leaves entire or obscurely serrate; fruit small.
(C. Mississippiensis) SUGARBERRY 3. Genus PLANERA, Gmel.
Water-loving trees of small size. Leaves elm-like, small. unsymmetrical. Flowers polygamo-moncecious, axillary, small, Fruit a dry drupe in crustaceous husk. (P. aquatica) PLANER TREE