First published in: Ann. Sci. Nat., Bot. ser. 3, 5: 7, t.1 (1846)

Etymology: From the Greek ceratos a horn, and Zamia a cycad, referring to the horned sporophylls

Description: Habit: dioecious palm- or fern-like shrubs with aerial or subterranean, pachycaul, cylindrical or globose stems, with few to many leaves. Leaf bases mostly not persistent. New leaves emerging singly or in flushes. Dichotomous branching common in geophytic species, basal offsets ("suckers") produced by some species. Leaves: pinnate, spirally arranged, interspersed with cataphylls, lower leaflets not reduced to spines. Petioles often with prickles. Longitudinal ptyxis erect, horizontal ptyxis erect. Leaflets simple, entire, with numerous bifurcating parallel veins and no distinct midrib, leaflets articulated, inserted near the edges of the rhachis towards the adaxial side, lacking a differently coloured basal gland; stomata on lower surface only or on both surfaces; epidermal cells elongated parallel to long axes of leaflets. Leaves pubescent, at least when young, with unbranched, transparent and coloured hairs. Microsporophylls: spirally orthostichous, aggregated into usually stalked male cones and each with a faceted sterile apex bearing two distinct, spreading stout spines or horns. Each microsporophyll bearing numerous microsporangia (pollensacs) on the abaxial surfaces. Microsporangia opening by slits. Pollen cymbiform, monosulcate. Megasporophylls: spirally orthostichous, aggregated into stalked or sessile female cones. Sporophylls simple, appearing peltate with a hexagonal, faceted dilated apex bearing two distinct, spreading stout spines or horns. Ovules two (rarely three), sessile, orthotropous, inserted on the inner (axis-facing) surface of the thickened lamina and directed inwards ("inverted"). Seeds: subglobular to oblong or ellipsoidal, with a cream or white fleshy outer sarcotesta. Endosperm haploid, derived from the female gametophyte. Embryo straight; with 2 cotyledons that are usually united at the tips and a very long, spirally twisted suspensor. Seeds radiospermic; germination cryptocotular.