Ceratozamia Brongn., Ann. Sci. Nat., Bot. ser. 3, 5: 7, t. 1. 1846.

Martinez-Dominguez, Lili, Nicolalde-Morejon, Fernando, Vergara-Silva, Francisco & Stevenson, Dennis Wm., 2022, Monograph of Ceratozamia (Zamiaceae, Cycadales): an endangered genus, PhytoKeys 208, pp. 1-102 : 1

Ceratozamia Brongn., Ann. Sci. Nat., Bot. ser. 3, 5: 7, t. 1. 1846.

Type species.

Ceratozamia mexicana Brongn.

Description.

Stem 10-250 cm long, 8-40 cm in diameter, epigeous or semi-hypogeous, erect or decumbent. Cataphylls persistent, triangular to narrowly triangular, reddish brown, tomentose to densely tomentose at emergence, partially tomentose at maturity, apex acuminate. Leaves stipulate, ascending to descending, light green or reddish brown at emergence with whitish gray or brown trichomes, generally glabrous at maturity; stipulate 2-6 cm long, linear, tomentose at maturity. Petiole straight or twisted, sometimes brown in mature leaves, without prickles or heavily to lightly armed with prickles; prickles can be bifurcate. Rachis straight or twisted, without prickles or armed with prickles up to half the length of the leaves. Leaflets articulate, sessile, membranaceous to coriaceous, linear to obovate, opposite to subopposite or clustered, not imbricate, generally acuminate at apex, attenuate at base, margins entire; articulations green to brown. Pollen strobili 1-2, with sterile tip, erect, cylindrical, green to cream with blackish to reddish brown trichomes at maturity; pollen sporangiophores deltoid to cuneate, basally stalked, distal face bicornate, fertile abaxial surface with 24-280 sporangia in clusters of (2)3(4-5), dehiscent by longitudinal slit; peduncle pubescent to tomentose. Ovulate strobili usually solitary, globose to cylindrical; green with pale pink to blackish trichomes at maturity, acute to apiculate apex; ovulate sporangiophores peltate with a narrow basal stalk and transversely hexagonal tips, bicornate at distal end; peduncle pubescent to tomentose, erect to pendulous. Seeds (ovules) 2 per megasporophyll projecting inward toward the strobilus axis, spherical, sarcotesta pink to yellowish when immature, light brown at maturity, sclerotesta smooth with several furrows longitudinal from micropylar end.

Distribution and habitats.

The 36 species of Ceratozamia are only found from Mexico to Central America, usually in montane habitats on limestone soils at elevations from 19 to 2,000 m. Most of the species are narrowly endemic, and all are on CITES Appendix I.