GUAIACUM (from Guaiac, its South American name). ORD. Zygophylleae. A genus containing about eight species of lofty stove evergreen trees or shrubs, inhabiting the West Indies and sub-tropical North America. Flowers blue or purple; peduncles axillary, one-flowered. Leaves opposite, abruptly pinnate; leaflets entire. Guaiacums require a compost of rich, sandy, fibry loam. Propagated from ripened cuttings, obtained in April, and inserted in sandy soil, under a hand glass, in heat. GUAIACUM arborea (tree-like). fl. blue, disposed in loose racemes. July. l. with seven to fourteen pairs of oval-oblong, blunt leaflets, which are unequal at the base, and are usually alternate. h. 40ft. Carthagena, 1816. GUAIACUM officinale (officinal).* Lignum Vitae. fl. blue; peduncles twin. July. l. with two pairs of obovate or oval blunt leaflets. Bark smooth, variegated with green and white; wood with a peculiar acid aromatic scent. h. 30ft. Jamaica, 1694. (B. M. Pl. 41; B. R. 1839, 9.) This species yields the Lignum Vitae, a greenish-brown, hard, heavy wood, extensively used by turners; and also the fragrant resin commonly called gum guaiacum, which, as well as the bark and wood, is used medicinally.