_Plants with simple or compound leaves, dotted with pellucid glands and abounding with a pungent or bitter-aromatic acrid volatile oil, producing hypogynous almost always regular 3--5-merous flowers, the stamens as many or twice as many as the sepals (rarely more numerous); the 2--5 pistils separate or combined into a compound ovary of as many cells, raised on a prolongation of the receptacle (gynophore) or glandular disk._--Embryo large, curved or straight, usually in fleshy albumen. Styles commonly united or cohering, even when the ovaries are distinct. Fruit usually capsular. Leaves alternate or opposite. Stipules none.--A large family, chiefly of the Old World and the southern hemisphere; our two indigenous genera are 1. Xanthoxylum. Flowers diœcious; ovaries 3--5, separate, forming fleshy pods. 2. Ptelea. Flowers polygamous; ovary 2-celled, forming a samara, like that of Elm. 1. XANTHÓXYLUM, L. PRICKLY ASH. Flowers diœcious. Sepals 4 or 5, obsolete in one species. Petals 4 or 5, imbricated in the bud. Stamens 4 or 5 in the sterile flowers, alternate with the petals. Pistils 2--5, separate, but their styles conniving or slightly united. Pods thick and fleshy, 2-valved, 1--2-seeded. Seed-coat crustaceous, black, smooth and shining. Embryo straight, with broad cotyledons.--Shrubs or trees, with mostly pinnate leaves, the stems and often the leafstalks prickly. Flowers small, greenish or whitish. (From ξανθός, _yellow_, and ξύλον, _wood_.) 1. X. Americànum, Mill. (NORTHERN PRICKLY ASH. TOOTHACHE-TREE.) Leaves and flowers in sessile axillary umbellate clusters; leaflets 2--4 pairs and an odd one, ovate-oblong, downy when young; calyx none; petals 4--5; pistils 3--5, with slender styles; pods short-stalked.--Rocky woods and river-banks; common, especially northward. April, May.--A shrub, with yellowish-green flowers appearing before the leaves. Bark, leaves, and pods very pungent and aromatic. 2. X. Clàva-Hérculis, L. (SOUTHERN P.) Glabrous; leaflets 3--8 pairs and an odd one, ovate or ovate-lanceolate, oblique, shining above; flowers in an ample terminal cyme, appearing after the leaves; sepals and petals 5; pistils 2--3, with short styles; pods sessile. (X. Carolinianum, _Lam._)--Sandy coast of Virginia, and southward. June.--A small tree with very sharp prickles. 2. PTÈLEA, L. SHRUBBY TREFOIL. HOP-TREE. Flowers polygamous. Sepals 3--5. Petals 3--5, imbricated in the bud. Stamens as many. Ovary 2-celled; style short; stigmas 2. Fruit a 2-celled and 2-seeded samara, winged all round, nearly orbicular.--Shrubs, with 3-foliolate leaves, and greenish-white small flowers in compound terminal cymes. (The Greek name of the Elm, here applied to a genus with similar fruit.) 1. P. trifoliàta, L. Leaflets ovate, pointed, downy when young.--Rocky places, Long Island to Minn., and southward. June.--A tall shrub. Fruit bitter, used as a substitute for hops. Odor of the flowers disagreeable. * * * * *