ZANTHOXYLUM (from xanthos, yellow, and xylon, wood; alluding to the colour of the roots). Sometimes spelt Xanthoxylon. Prickly Ash; Toothache-tree. SYN. Pterota. Including Blackburnia and Fagara. ORD. Rutaceae. A genus embracing about eighty species of stove, greenhouse, half-hardy, or hardy shrubs or trees, often armed with stout prickles, inhabiting tropical and sub-tropical regions. Flowers often white or greenish, small, in axillary or terminal, pedunculate, broad or narrow cymes; calyx three to five-cleft, rarely obsolete; petals three to five, rarely wanting; stamens three to five. Fruit of one to five fleshy carpels, often aromatic or strongly scented. Leaves alternate, trifoliolate or unequally pinnate; leaflets opposite or alternate, entire or crenate, often oblique, dotted. A selection of the introduced species is here given. For culture, see Zizyphus. ZANTHOXYLUM alatum (winged). fl. apetalous; panicles loose, sparingly branched. Spring. l. 1 1/2in. to 9in. long; leaflets two to six pairs, lanceolate, obtusely acuminate, glabrous beneath; petiole and rachis usually broadly winged. Prickles often vertically flattened on the trunk and branches. India. Half-hardy shrub or small tree. ZANTHOXYLUM americanum (American). Common Toothache-tree. fl. apetalous, in axillary umbels. March and April. l., leaflets nine or eleven, ovate, obscurely serrated, equal at base; petioles round, and devoid of prickles; stipules replaced by prickles. h. 12ft. to 15ft. North America, 1740. Hardy tree. ZANTHOXYLUM aromaticum (aromatic). fl. greenish-white; panicles terminal and axillary, glabrous, verrucose, 3in. to 5in. in diameter. April. l., leaflets six to twelve-jugal, elliptic or oblong, crenate, with the crenatures broadly truncate, petiolulate, glabrous, glandular beneath. Prickles short, subulate, or wanting. h. 20ft. Jamaica, 1824. Stove tree. ZANTHOXYLUM Blackburnia (Blackburnia). fl. white; petals imbricated; panicles axillary or terminal, loose, shorter than the leaves. May. l. pinnate, with a compound petiole of 4in. to 8in.; leaflets three to nine, very obliquely ovate, shortly acuminate, usually 2in. to 3in. long, petiolulate. h. 6th. Australia, 1829. Greenhouse shrub or small tree. SYN. Blackburnia pinnata. ZANTHOXYLUM clava-Herculis (Hercules' Club). Southern Prickly Ash. fl. greenish; panicles terminal and axillary, pubescent, 2in. to 4in. in diameter. April. l., leaflets five to ten-jugal, lanceolate-oblong, pointed, quite entire or minutely serrated, sub-sessile, glabrous above, puberulous along the nerves or glabrate beneath. h. 20ft. to 50ft. West Indies, 1824. Stove tree. ZANTHOXYLUM nitidum (shining). fl. greenish-white; racemes axillary, fascicled. May. l. imparipinnate, two or three-jugal; leaflets oblong, shining, remotely glandular-crenate, elongated and emarginate at apex, the midrib (as well as the petioles and branches) prickly. h. 10ft. China, 1823. Greenhouse shrub. (B. M. 2558.) ZANTHOXYLUM piperitum (Pepper-like). Chinese or Japanese Pepper. fl. white. September. l., leaflets oblong, unequal at base, crenate; petioles subulate, jointed; prickles stipular. h. 10ft. Japan, 1773. Half-hardy shrub. The small, globose, rugose fruits of this species are called Japan Pepper. SYN. Fagara piperita. ZANTHOXYLUM Pterota (Pterota). Bastard Ironwood. fl. greenish, in axillary clusters, single or by pairs; stamens four. August. l., leaflets seven to nine, 1/2in. to 3/4in. long, obovate, crenate above the middle, sessile; petioles winged, jointed. Branches zigzag, armed with short, curved prickles. h. 10ft. South Florida, &c., 1768. Half-hardy tree. ZANTHOXYLUM spinifex (thorny). fl. white, in a short glomerule. July. l., leaflets one to three-jugal, oval or spathulate, emarginate or blunt, quite entire, 1/4in. to 1/2in. long, glabrous, leathery, bitubercled at the base beneath, devoid of pellucid dots; petioles unarmed. Stipular prickles straight. West Indies, 1825. A low, tortuous, leafy, stove shrub. SYN. Fagara microphylla.