Tetradium
Lour.
Shrubs or trees, evergreen or deciduous, dioecious or monoecious. Leaves opposite, imparipinnate; lateral leaflets petiolulate, terminal ones on an extension of rachis; leaflets ovate, oblong or oblong-lanceolate, or elliptic-obovate, acute to cuneate of obtuse to rounded and more or less oblique at base, acute or shortly to long acuminate at apex, margins entire or remotely to finely glandular-crenate, predominantly or rarely indistinctly gland-dotted, chartaceous to coriaceous, glabrous or glabrate to pubescent, green above, pale beneath, brown or glaucous when dry, pinnatelynerved. Inflorescence corymbose to paniculate, spreading or compact, few to many flowered, terminal or pseudoterminal (from uppermost leaf axils). Flowers abortively unisexual, 5- or 4-merous, greenish-white or yellow, bracteate, pedicellate. Sepals connate at base, valvate, ovate or orbicular. Petals ovate or elliptic-oblong, obtusely acuminate at apex, acumen deflexed, glabrous abaxially, glabrous to pilose adaxially. Stamens as many as petals; filaments linear-subulate, glabrous abaxially, villous adaxially; anthers dorsifixed, ovoid or oblong, obtuse. Staminodes much shorter than petals, rarely persistent in fruits. Disk intrastaminal, conical to cylindrical in staminate flowers or pulvinate to barrel shapecl in carpellate flowers, persistent in fruits. Gynoecium 5- or 4-carpellate, ovary 5- of 4-lobed, 5- or 4-locular, subglobose to obovoid, glabrous, punctate, ovules 2 or 1 per locule; style apical, short; stigma capitate. Pistillodes 3 - 5, free or connate at base. subulate, glabrous or hairy. Fruits of 1 - 5, 1 or 2-seeded follicles, free to the base or connate up to middle from base, excocarp coriaceous or subwoody, glabrous to shord, pubescent, glandular-punctate, endocarp cartilaginous to pergamantaceous; undeveloped carpels persistent in fruits; seeds persistent in dehisced follicle, ellipsoid or subtrigonal, shiny, smooth, black or brown, arillate, albuminous; embryo straight; cotyledons ellipsoid.
Subtropical and temperate regions of the Old World, E. Himalayas to Japan to Java and Sumbawa 9 species, 3 in India.
Literature. HARTLEY, T.G. (1981) A revision of the genus Tetradium (Rutaceae). Gird. Butt. Straites Settlem. 34: 91 - 131.
Notes. Tetrudium has long been regarded as a synonym of Euodia J.R. & G. Forst. until Hartley (1981) reviewed and discussed taxonomic delimitations in Tetradium and related genera. He concluded that those plants with opposite, pinnately compound leaves and follicular fruits with persistent seed form a natural group around the type species of Tetradium and stand well apart morphologically, from a group of species centered around the type species of Euodia. Sexual dimorphism observed in gynoecium of Tetradium spp. also substantiates the reason for separating it as a distinct genus from Euodia and Melicope.
Subtropical and temperate regions of the Old World, E. Himalayas to Japan to Java and Sumbawa 9 species, 3 in India.
Literature. HARTLEY, T.G. (1981) A revision of the genus Tetradium (Rutaceae). Gird. Butt. Straites Settlem. 34: 91 - 131.
Notes. Tetrudium has long been regarded as a synonym of Euodia J.R. & G. Forst. until Hartley (1981) reviewed and discussed taxonomic delimitations in Tetradium and related genera. He concluded that those plants with opposite, pinnately compound leaves and follicular fruits with persistent seed form a natural group around the type species of Tetradium and stand well apart morphologically, from a group of species centered around the type species of Euodia. Sexual dimorphism observed in gynoecium of Tetradium spp. also substantiates the reason for separating it as a distinct genus from Euodia and Melicope.
KEY TO THE SPECIES
| 1a. Flowers predominantly 4-merous; anthers broadly oblong, shorter than filaments; follicles 2-seeded | 1. Tetradium fraxinifolium |
| b. Flowers predominantly 5-merous; anthers ovoid, longer than filaments; follicles 1-seeded | 2 |
| 2a. Leaf rachis stout, velvety; leaflets velvety or woolly beneath with prominent oil dots | 3. Tetradium ruticarpum |
| b. Leaf rachis slender, glabrous or with abort soft white, spreading hairs; leaflets glabrous beneath with inconspicuous/diffuse oil dots | 2. Tetradium glabrifolium |
