Ulmaceae
Monoecious or hermaphroditic trees with watery sap. Leaves alternate, simple, serrate or entire, oblique at base, stipulate, the stipules caducous. Flowers small, greenish, rather inconspicuous, zygomorphic or actinomorphic, in fascicles, racemes, or solitary. Calyx synsepalous, 4-8 lobed, green or brownish; petals absent; stamens 4-8, opposite the calyx lobes; pistil 1, carpels 2, stigmas 2, ovary superior. Fruit a samara, drupe, or nutlet.
Fruit a drupe; leaves with 3 principal veins..........................................................................Celtis
Fruit a samara or bur-like o rnutlet; leaves with only one principal vein.
Fruit a samara; leaves usually pubescent beneath, elliptic...........................................Ulmus
Fruit a bur-like nut or nutlet; leaves mostly glabrous beneath, ovate........................Planera
ULMUS
PLANERA
CELTIS
Fruit a drupe; leaves with 3 principal veins..........................................................................Celtis
Fruit a samara or bur-like o rnutlet; leaves with only one principal vein.
Fruit a samara; leaves usually pubescent beneath, elliptic...........................................Ulmus
Fruit a bur-like nut or nutlet; leaves mostly glabrous beneath, ovate........................Planera
ULMUS
PLANERA
CELTIS