8U TREES OF THE NORTHERN UNITED STATES 
long, alternate, oblong, wavy and obscurely serrulate, nearly smooth, 
on slender pubescent petioles. Flowers greenish, 5-parted, solitary 
or in umbellate clusters in the axils. Fruit berry-like, globular, 
the size of peas, 3-seeded, red and finally black in winter. A thorn- 
less shrub or small tree, 5 to 20 ft. high. New Jersey, south and 
west. Usually a shrub except in the South- 
ern States. 
3. Rhaémnus Californicus,Esch. (CaL- 
IFORNIA BUCKTHORN.) Leaves evergreen, 
oval-oblong to elliptical, 1 to 4 in. long, 
rather obtuse, sometimes acute, generally 
rounded at base, serrulate or entire. Fruit 
blackish purple, with thin pulp, 4 in., 2- 
_ to 3-seeded. A spreading shrub, 5 to 18 ft. 
R. Californicus, high, without thorns; from California. 
GENUS 21. HOVENTIA. 
Leaves alternate, deciduous, simple, oblique at base. 
Fruit an obscurely 3-lobed, 3-celled, 3-seeded pod in 
dichotomous clusters, both axillary and terminal. 
Hovénia dalcis, Thunb. Leaves long- 
petioled, more or less ovate to cordate, 
serrate, palmately 3-ribbed, much darker 
on the upper surface; both sides slightly 
roughened with scattered hairs. Fruit 
sweet, edible, in clusters in the axils of 
the leaves; seeds lens-shaped, with a ridge 
on the inner side. Flowers white; in July. 4 
A large, broad-topped tree, introduced H. dalcis. 
from Japan. Hardy at Washington, but dies to the ground in the 
Arnold Arboretum, Massachusetts. 
Genus 22. ZIZYPHUS. 
Leaves simple, alternate, deciduous, 3-ribbed. Flowers 
axillary, 5-petaled. Fruit fleshy, drupe-like, containing 
a 1- to 2-celled nut. 
Zizyphus vulgaris, Lam. (JusuBz.) Leaves ovate-lanceolate, 
obtuse, serrate, smooth, and glossy green on both sides, upper side 
