XXVI. RUTACEÆ.
Trees or shrubs, abounding in a pungent or bitter aromatic volatile oil, with simple or compound usually glandular-punctate leaves, without stipules or rarely with stipular spines. Flowers regular, perfect or unisexual, in paniculate or corymbose cymes; calyx 3—5-lobed, the lobes more or less united at base, imbricated in the bud; petals 3—5, imbricated in the bud; stamens as many or twice as many as the petals; filaments distinct or united below; anthers introrse, 2-celled, the cells opening longitudinally; pistils 1—4, separate or united into a compound ovary sessile or stipitate on a glandular disk; styles mostly united; ovules usually 2 in each cell of the ovary, pendulous, anatropous or amphitropous; raphe ventral; micropyle superior. Fruit of 2-valved carpels, a samara, drupe or capsule. Seeds solitary or several; seed-coat bony or crustaceous, furrowed or punctate; embryo axile in fleshy albumen; radicle short, superior.
Of this large family, widely distributed over the warm and temperate parts of the earth’s surface, four genera only have arborescent representatives in the United States. Citrus Aurantium L., the Bitter-sweet Orange, a native of Asia, has long been naturalized in the peninsula of Florida, where other species of this genus have escaped from cultivation and are now growing spontaneously.
CONSPECTUS OF THE ARBORESCENT GENERA OF THE UNITED STATES.
Fruit of 1—5, 2-valved 1-seeded carpels; flowers diœcious or polygamous.1. [Xanthoxylum.] Fruit of 3 or 4-winged indehiscent 1-seeded carpels; flowers perfect.2. [Helietta.] Fruit a winged samara; flowers polygamous.3. [Ptelea.] Fruit a 1-seeded drupe; flowers perfect or polygamous.4. [Amyris.]