Exacum
(a name used by Pliny, and derived by him from ex, out, and ago, to drive; in allusion to its supposed expelling powers). ORD. Gentianeae. A genus containing about a score species of very pretty, erect, stove or greenhouse, annual, biennial, or perennial herbs, natives of India and Eastern Asia, the Malayan Arohipelago, and Socotra. Flowers terminal and axillary; corolla salver-shaped or sub-rotate, with a globose or ventricose tube. Leaves opposite, decussate, sessile. The species are not often seen in gardens. They thrive best in a compost of peat and turfy loam, in equal proportions, and a plentiful supply of water is necessary. Seeds should be sown in April, and placed in bottom heat, and the seedlings carefully shifted into larger pots as required. Several other species of this elegant genus, besides those given below, are well worth growing, but as yet await introduction. E. affine (related). fl. bluish-lilac, agreeably scented; stamens yellow. Summer and autumn. l. stalked, broadly ovate. h. 6in. Socotra, 1882. A compact-habited, free-flowering, warm greenhouse biennial. (G. C. n. s., xxi. 605.) E. macranthum (large-flowered).* fl. about 2in. across, of a deep rich blue-purple colour, with large bright yellow stamens, disposed in terminal and axillary, corymbose heads. December. l. large, glabrous, glossy. h. 1 1/2ft. Ceylon, 1853. Stove biennial. (B. M. 4771.) E. zeylanicum (Ceylon).* fl. of a beautiful violet colour; petals five, obovate; racemes terminal and axillary, forming an expanded, terminal, corymb-formed panicle. September. l. nearly sessile, ovate-lanceolate, acuminated. Stem and branches tetragonal. h. 1ft. to 2ft. Ceylon, 1848. Stove biennial. (B. M. 4423.)