544 



The Green Barked Acacias 



pearing from April until June, often before the leaves, in few-flowered racemes 

 about 2.5 cm. long, on slender pedicels 6 to 10 mm. long; the calyx- tube is short, 

 its reflexed lobes deciduous; petals obovate, about 5 mm. long, spreading; stamens 

 somewhat longer than the petals; ovary stalked and hairy. The pods, which 

 hang on the branches for a long time, are cyHndric, 5 to 8 cm. long, 10 to 12 mm. 

 thick, tapering toward each end, long-stalked and constricted between the i to 3 

 seeds, which are elliptic, a Httle flattened, about 10 mm. long, pale and brown. 

 The wood is hard, close-grained, dark yellow-brown with yellow sapwood; the 

 specific gravity is about 0.74. 



VI. THE GREEN BARKED ACACIAS 



GENUS CERCIDIUM TULASNE 



''BOUT 5 species of trees and shrubs, with stout, crooked branches, 

 bright green bark, and sharp axillary spines, compose the genus 

 Cercidiuni. They occur only in the warmer portions of the western 

 hemisphere. Three species are known from our area, 2 of which 

 are arborescent. 



The leaves are alternate, early deciduous, bipinnate, small, stalked, and usually 

 without stipules. The flowers are very showy, nearly regular, few in axillary 

 racemes; the calyx is tubular or bell-shaped, and persistent, its 5 pointed lobes 

 reflexed; corolla golden yellow, of 5 broad nearly equal petals; stamens 10, borne 

 on the margin of a disk, the upper one swollen near the base, the filaments free 

 and hairy; anthers 2-celled, opening lengthwise; ovary short-stalked, smooth or 

 hairy; style slender, the stigma very small. The fruit is a flat or somewhat 

 swollen legume, at length dehiscent; the seeds, placed lengthwise in the pod on 

 long stalks, are ovate, hard and flattened with thin homy endosperm. 



The name apphed to these plants is the Greek name of a weaver's instrument, 

 of which the shape of the pod is suggestive; the type species is C. spinosum 

 Tulasne, of South America. Our arborescent species are: 



Leaflets green, somewhat glandular, not glaucous; pod flat. i. C. jloridum. 



Leaflets glaucous; pod somewhat swollen 2. C. Torreyanum. 



I. GREEN BARKED ACACIA Cercidium floridum Bentham 



This small tree, with its bright green branches and golden-yellow flowers, is a 

 conspicuous object in extreme southern Texas, where it occurs but sparingly, be- 

 coming more common, however, southward in adjacent Mexico. It is a low, 

 crooked, wide-spreading tree, attaining a height of 6 meters, with a trunk diameter 

 of 2.5 dm. 



The bark is about 2 mm. thick, light greenish brown, smooth or nearly so. 

 The twigs are slender, sHghtly zigzag, smooth or nearly so, olive-green, bearing 



