XXXVIII. RHAMNACEÆ.
Trees or shrubs, with scaly or naked buds, watery bitter astringent juice, simple leaves, and minute deciduous stipules (persistent in Krugiodendron). Flowers small, mostly greenish, perfect (polygamo-diœcious in one species of Rhamnus); calyx 4—5-lobed, the lobes valvate in the bud; petals 4—5, inserted on the calyx near the margin of the conspicuous disk lining the short calyx-tube, and infolding the stamens, or 0; stamens as many as and alternate with the calyx-lobes, free, inserted at or below the margins of the disk; filaments slender, subulate; anthers introrse, versatile, 2-celled, the cells opening longitudinally; pistils of 2—3 united carpels; ovary 2—3-, or rarely 1-celled by abortion, partly immersed in the disk; style terminal; stigma 2—4-lobed; ovules 1 in each cell, erect, anatropous; raphe ventral; micropyle inferior. Fruit drupaceous, supported on the tube of the calyx and bearing the remnants of the style. Seed usually with scanty oily albumen; embryo with broad cotyledons; radicle inferior, next the hilum.
CONSPECTUS OF THE ARBORESCENT GENERA OF THE UNITED STATES.
Fruit more or less fleshy. Fruit with a single stone; petals 0. Sepals without crests. Leaves alternate; branches spinescent.1. [Condalia.] Leaves nearly opposite; branches not spinescent.2. [Reynosia.] Sepals crested; leaves mostly opposite.3. [Krugiodendron.] Fruit with 2 or 3 nutlets; petals 4 or 5, or 0; leaves alternate.4. [Rhamnus.] Fruit crustaceous, 3-lobed, separating into 3 longitudinally 2-valved nutlets. Sepals inflexed; petals narrowed into a long slender claw.5. [Ceanothus.] Sepals spreading; petals sessile.6. [Colubrina.]