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| The Cycad Pages
| | GENUS
Ceratozamia
| |
D.W. Stevenson | |
Ceratozamia Brongn., Ann. Sci. Nat. Bot., sér. 3, 5: 7-8 (1846);
from the Greek ceratos a horn, and Zamia a cycad, referring
to the horned sporophylls.
Type: Ceratozamia mexicana Brongn.
15 species; 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
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C. alvarezii
C. euryphyllidia
C. hildae
C. kuesteriana
C. latifolia
C. matudae
C. mexicana
C. microstrobila
C. miqueliana
C. mixeorum
C. morettii
C. robusta
C. norstogii
C. sabatoi
C. whitelockiana
C. zaragozae
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.
IDENTIFICATION KEYS
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.
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, to 3 cm wide --
Ceratozamia microstrobila
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
- 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 streptorachis
- 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
