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Key to Species — Part 31

A. Leaves deciduous. (Eastern.)

(R. Caroliniana) INDIAN CHERRY

AA. Leaves evergreen, or nearly so. (Western.)

B. Length, 1/3 to 1 1/2 inches, holly-like.

(R. crocea) EVERGREEN BUCKTHORN

BB. Length, 1 to 7 inches, deciduous or persistent.

(R. Purshiana) CASCARA BUCKTHORN

The buckthorns are small, ornamental tree and shrubs. There are sixty species of them, widely distributed in the Northern Hemisphere, with a few tropical species, and representatives in South Africa and Brazil.

Of our three natives, the Indian cherry is rarely seen in cultivation. When people plant buckthorns they order them of nurserymen who offer the vigorous English Rhamnus cathartica, a clean-leaved, handsome, thorny shrub, beset in autumn with black berries clustered close to the twigs. Its fruit yields a valuable medicinal principle, oftenest sold in the form of a syrup. The bark furnishes a yellow dye. Another European buckthorn, R. frangula, appears in our shrubbery borders, its shining leaves brightened by large red berries. The wood of this species makes valuable charcoal for gunpowder.

Morocco leather is dyed yellow with the berry of a French buckthorn. Painters get their "China green" from two Chinese species. Jujube paste is made from the fruit of a member of this family. The "Lotus-eaters" of ancient literature are now believed to have tasted--to their undoing--the fruit of one of the buckthorns.

Indian Cherry, Yellow Buckthorn (Rhamnus Caroliniana, Walt.)--A slender, spreading tree, 25 to 35 feet high, or a tall shrub; branches thornless. Bark ashy grey, blotched with black, shallowly furrowed; branches grey. Wood hard, light brown, close, brittle. Buds pointed, small. Leaves deciduous, alternate, elliptical, acute, faintly serrate, 2 to 5 inches long, yellow-green above, paler beneath; veins yellow. Flowers small, in axillary umbels, April to June. Fruits, September; berry-like, 2 to 4 celled drupes, with dry, sweet, black flesh, red before it ripens. Preferred habitat, rich bottom lands and limestone hillsides. Distribution, Long Island to Florida; west to Nebraska and Texas. Uses: Sometimes planted as an ornamental for its bright berries. Not hardy North.

The Cascara Buckthorn (R. Purshiana, DC.) grows from Puget Sound through California, and east to Colorado and Texas. It is extremely variable in size, adapting itself to different regions and climates with great facility. In the canons of the Sierras it becomes a tree 40 feet high; on the exposed mountain sides and on the arid coast of California it dwindles to a prostrate shrub. Its elliptical leaves are usually evergreen or half evergreen; the fruits turn red on ripening, then black.

It is from the bark of this tree that the drug, Cascara Sagrada, is obtained. The species and its varieties are planted in shrubberies for their pretty foliage and bright fruits. Forms with deciduous leaves are hardy in Massachusetts gardens.

The Evergreen Buckthorn (Rhamnus crocea, Nutt.) grows on the western slopes of the Sierra Nevada Mountains in California, south of the upper valley of the Sacramento River. It is more often a shrub than a tree, and commonly forms thickets on the shaded sides of ravines. Its leaves are almost round and spiny-toothed, glossy green above and coppery beneath. Its scarlet, pea-like fruits are sweet and edible. This buckthorn is frequently seen in gardens in California. It is not hardy in the North, but deserves introduction into the Southern and Middle States.

Numerous related genera belonging to the buckthorn family are found in the Southern States and in California. Among them are trees of unusual interest which deserve brief mention here.

Some are remarkable for the hardness of their wood, others for their flowers.

The Red Ironwood (Reynosia septentrionalis, Urb.), called also "Darling plum," grows wild in southern Florida, and is cultivated to some extent for its fruit. It is a pretty little tree, clothing its heavy, hard wood with bright red bark. The purple or black plums are sweet and of pleasant flavour.

The Bluewood, or Logwood (Condalia obovata, Hook.), grows in thickets in the valley of the Rio Grande River in Texas and is especially esteemed as fuel. It burns with an unusually fervent heat. Its leaves are dry and leathery, obovate, entire, and scarcely an inch long. Its twigs end in sharp thorns. The sweet berries ripen, turning blue, then black, during the long summer. The wood is red, but yields a bluish dye. It is an entirely different tree from the logwood of commerce, Hoematoxylon Campechianum, which grows in Central America and the West Indies and yields a colouring matter used in calico printing and in the preparation of lake pigments.

The Black Ironwood (Krugiodendron ferreum, Urb.) grows plentifully in second-growth timber in southern Florida and in the West Indies. Its velvety green twigs are covered with small, oval, leathery leaves, and in autumn with solitary black berries. The bark is pale grey.