Monographs Details: Vachellia farnesiana (L.) Wight & Arn.
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - The Spanish popular name Aroma is well applied to this shrub, or small tree, its small, bright yellow, tufted flowers being deliciously fragrant, and much used in perfumery. It is plentiful in the dry parts of Porto Rico, at lower elevations, commonly growing in thickets; we have not observed it at altitudes higher than about 150 meters. Geographically it is distributed nearly throughout tropical and subtropical America, ranging north into Florida, Louisiana, and Texas, and naturalized in tropical parts of the Old World. It was first known to botanists from Santo Domingo. It is the only species of its genus in the Porto Rico Flora. Vachellia (named in honor of Rev. C. H. Vachell, a missionary and botanical collector in China) consists of few species of shrubs or small trees, armed by spinescent stipules. Their twice compound leaves have many pairs of small, narrow leaflets. The small, more or less imperfect flowers are borne in stalked, round heads; the calyx is 5-toothed, the corolla tubular-funnelform, and 5-toothed, the numerous stamens with slender filaments, separate from each other, and small anthers; the stalkless ovary contains few, or several ovules, and the style is slender. The pod is rather long, nearly circular in cross-section, woody or leathery in texture, pulpy within, and opens very tardily, or falls away without opening, the seeds in 2 rows. Vachellia Farnesiana (commemorates Cardinal Odoardo Farnese, who grew the tree in his Roman garden, prior to 1612), is usually a much-branched shrub about 3 meters high, or lower, but rarely forms a tree up to about 9 meters high, the twigs slender. The leaves are from 5 to 10 centimeters long, and bear a small gland on the usually hairy, short stalk; the stipular spines are whitish, from 0.5 to 5 centimeters long; there are from 2 to 6 pairs of primary leaf-divisions, each division with from 10 to 25 pairs of narrow, blunt leaflets from 3 to 5 millimeters long. The hairy stalks of the flower-heads are from 2 to 4 centimeters long, the heads of yellow flowers about 12 millimeters in diameter; the stamens are more than twice as long as the corolla. The pod is usually somewhat curved, smooth, from 4 to 7 centimeters long, about 1 centimeter in diameter.

Discussion:Aroma Cashaw Mimosa Family Mimosa Farnesiana Linnaeus, Species Plantarum 521. 1753. Acacia Farnesiana Willdenow, Species Plantarum 4: 1083. 1805. Vachellia Farnesiana Wight and Arnott, Prodromus Florae Peninsulae Indiae Orientalis 272. 1834.