The Cycad Pages
GENUS  Ceratozamia
D.W. Stevenson

Ceratozamia Brongn., Ann. Sci. Nat. Bot., sÚr. 3, 5: 7-8 (1846); from the Greek ceratos a horn, and Zamia a cycad, referring to the horned sporophylls. Type: Ceratozamia mexicana Brongn.
A genus of 16 species (plus several undescribed) in the family Zamiaceae; Mexico, Guatemala & Belize
Named by 19th Century French botanist and palaeobiologist Adolphe Theodore Brongniart (1801-1876) in 1846.
Distinguishing characters:

  • Leaves pinnate
  • Leaflets lacking a midrib
  • Leaflets articulated
  • Sporophylls in vertical rows in cones
  • Sporophyll apices with prominent paired horns

Select a species, or go to the keys to species
Individual species pages will have literature references and synonyms, and eventually images, distribution maps, descriptions and general notes on the species. These are not yet all in place for all species, but the database is slowly growing. On species pages, click on thumbnail images to see full-screen images (Red dot indicates that a page has at least one image; green dot indicates that a page has a complete treatment). links to images of type specimens held by the New York Botanical Garden (NY). links to images of the protologue or original description pertaining to the name.

    C. alvarezii
Red dot C. euryphyllidia
Red dot C. hildae
Red dot C. kuesteriana
Red dot C. latifolia
    C. matudae
Red dot C. mexicana
Red dot C. microstrobila
Red dot C. miqueliana
    C. mirandae
    C. mixeorum
Red dot C. morettii
Red dot C. norstogii
Red dot C. robusta
    C. sabatoi
Red dot C. whitelockiana
    C. zaragozae
    C. zoquensis

Genus 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.

Try this experimental multiple-entry key based on the DELTA format.
There is also a more traditional dichotomous key lower on the page.
To use this key, start with one or two characters that are clear. To refine a query, use the BACK button of your browser, return to the original query, and gradually add more characters.
Plant habit
Number of leaves
Leaf colour
Leaf length (cm)
Number of leaflets
Leaf bases
Rachis (twist)
Petiole: length, cm
Leaflets: arrangement
Leaflets: symmetry
Leaflets: texture
length, cm
width, mm
Pollen cone: colour
length, cm
diam., cm
peduncle (cm long)
Seed cone: colour
length, cm
diam., cm
peduncle (cm long)

Dichotomous key

1 Leaflets widest above the middle with oblique, abruptly acuminate apices
2 Leaflets clustered along the rachis -- Ceratozamia hildae
2* Leaflets evenly spaced
3 Leaflets less than 5 cm wide
4 Leaflets coriaceous
A leaflets to 3 cm wide -- Ceratozamia microstrobila
A* Leaflets 3-5 cm wide Ceratozamia zoquensis
4* Leaflets chartaceous to papyraceous, to 5 cm wide
5 Leaflets falcate upwardly -- Ceratozamia morettii
5* Leaflets not falcate -- Ceratozamia latifolia
3* Leaflets greater than 5 cm wide
6 Leaflets papyraceous to membranaceous, 5-8 cm wide -- Ceratozamia miqueliana
6* Leaflets translucent, 9-16 cm wide -- Ceratozamia euryphyllidia
6** Leaflets coriaceous, to 6.5 cm wide -- Ceratozamia zoquensis
1* Leaflets widest below the middle with acute or long attenuate apices
7 Leaflets strongly rolled adaxially, less than 10 mm wide
8 Rachis straight -- Ceratozamia norstogii
8* Rachis twisted
9 Petiole and rachis smooth -- Ceratozamia zaragozae
9* Petiole and rachis with numerous stout prickles -- Ceratozamia mirandai
7* Leaflets planate, margins sometimes revolute, greater than 1 cm wide
10 Leaflets 10-15 mm wide, abruptly cuneate basally, lanceolate, margins revolute
11 Petiole and rachis brownish, smooth or sparsely prickled -- Ceratozamia kuesteriana
11* Petiole and rachis green with numerous stout prickles
12 Rachis with prickles --
13 Leaflets 12-24 mm wide; leaflet veins 9-14 -- Ceratozamia sabatoi
13* Leaflets 4-9 mm wide; leaflet veins 5-9 -- Ceratozamia alvarezii
12* Rachis smooth -- Ceratozamia matudae
10* Leaflets 2-5 cm wide, gradually tapering basally, falcate to subfalcate, margins not revolute
13 Leaflets 2-3 cm wide, straight to subfalcate, coriaceous -- Ceratozamia mexicana
13* Leaflets 3-5 cm wide, falcate, papyraceous to subcoriaceous
14 Petioles sparsely prickled, prickles small -- Ceratozamia whitelockiana
14* Petioles densely prickled, prickles stout -- Ceratozamia robusta

The Cycad Pages

© 1998-2012 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill 1998-2010
Maintained by Leonie Stanberg and Dennis Stevenson 2010-2012
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