1. [Krugiodendron ferreum] Urb. Black Ironwood.
Leaves bright green and lustrous above, pale yellow-green below, glabrous with the exception of a few scattered hairs on the upper surface and on the petiole, 1′—1½′ long and ¾′—1′ wide, with entire or slightly undulate margins; persistent for two or three years; petioles stout, ¼′ in length. Flowers on bibracteolate pedicels ¼′ long, in 3—5-flowered cymes on peduncles sometimes ½′ in length, usually much shorter and often branched near the apex, on branchlets of the year; calyx about 1/16′ long. Fruit generally solitary, ⅓′ in length, on a stem ⅓′—½′ long.
A tree, sometimes 30° high, with a trunk 8′—10′ in diameter, and slender branchlets at first green and covered with dense velvety pubescence, becoming glabrous in their second year, and then gray faintly tinged with red and roughened by small crowded lenticels; generally much smaller and more often shrubby than arborescent. Bark of the trunk about ¼′ thick and divided into prominent rounded longitudinal ridges broken on the surface into short thick light gray scales. Wood exceedingly heavy, hard, strong, close-grained, brittle, rich orange-brown, with thin lighter colored sapwood.
Distribution. Florida, Cape Canaveral on the east coast to the shores of Bay Biscayne and on the Everglade Keys, Dade County, near Cape Sable, and on the southern keys; one of the commonest of the small trees of the region; on the Bahama Islands and on several of the Antilles.
4. RHAMNUS L.
Trees or shrubs, with terete often spinescent branches, without a terminal bud, scaly or naked axillary buds and acrid bitter bark. Leaves alternate or rarely obliquely opposite, conduplicate in the bud, petiolate, feather-veined, entire or dentate, stipulate. Flowers perfect or polygamo-diœcious, in axillary simple or compound racemes or fascicled cymes; calyx campanulate, 4—5-lobed, the lobes triangular-ovate, erect or spreading, keeled on the inner surface, deciduous; disk thin below, more or less thickened above; petals 5, inserted on the margin of the disk, ovate, unguiculate, emarginate, infolded round the stamens, deciduous, or 0; stamens 4 or 5; filaments very short; anthers oblong-ovoid or sagittate, rudimentary and sterile in the pistillate flower; ovary free, ovoid, included in the tube of the calyx, 2—4-celled, rudimentary in the staminate flower; styles united below, with spreading stigmatic lobes or terminating in a 2—3-lobed obtuse stigma; ovule erect from the base of the cell. Fruit drupaceous, oblong or spherical; flesh thick and succulent, inclosing 2—4 separable cartilaginous 1-seeded nutlets. Seeds erect, obovoid, grooved longitudinally on the back, with a cartilaginous seed-coat, the raphe in the groove, or convex on the back, with a membranaceous seed-coat, the raphe lateral next to one margin of the cotyledons; embryo large, surrounded by thin fleshy albumen; cotyledons oval, foliaceous, with revolute margins, or flat and fleshy.
Rhamnus with about sixty species is widely distributed in nearly all the temperate and in many of the tropical parts of the world with the exception of Australasia and the islands of the Pacific Ocean. Of the five species indigenous to the United States three attain the size of small trees. The fruit and bark of Rhamnus are drastic, and yield yellow and green dyes. The European Rhamnus cathartica L., the Buckthorn, has long been used as a hedge plant in northern Europe, and in eastern North America, where it has now become sparingly naturalized.
The generic name is from ῥάμνος, the classical name of the Buckthorn.