LON-CAPA Chigua


Chigua restrepoi
Photo Dennis Stevenson

The Cycad Pages

GENUS Chigua

D.W. Stevenson

Chigua D.W. Stev., Mem. New York Bot. Gard. 57: 169-172 (1990); from a Spanish rendering of the indigenous Indian name for cycads (most frequently applied to Zamia roezlii) in Panama and Colombia. Type: C. restrepoi D.W. Stev.

Described by American botanist Dennis Stevenson in 1990.

A genus in the family Zamiaceae, with two very rare species in South America (Colombia).

Key to species

Click on the name to go to the species page. Individual species pages will have photographs, distribution maps, descriptions, literature references 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.

Pinnae 15-25 cm long, 30-50 mm wide -- Chigua restrepoi Pinnae 30-35 cm long, 10-15 mm wide -- Chigua bernalii

Distinguishing characters:

Leaves pinnate
Leaflets with midrib and parallel longitudinal secondary veins
Leaflets articulated
Megasporophyll apices faceted or flattened, not spinose
Sporophylls in vertical rows in cones

Description:

Habit: dioecious fernlike shrubs with subterranean, pachycaul, globose stems, with few leaves. Leaf bases not persistent. New leaves emerging singly.

Leaves: pinnate, spirally arranged, interspersed with cataphylls, lower leaflets not reduced to spines. Petioles with prickles. Longitudinal ptyxis erect, horizontal ptyxis erect. Leaflets simple, with dentate margins, with numerous bifurcating parallel veins and a distinct midrib, leaflets articulated, inserted near the edges of the rhachis towards the adaxial side, lacking a differently coloured basal gland; stomata ? on both surfaces; epidermal cells elongated parallel to long axes of leaflets. Leaves pubescent, at least when young, with branched and simple, transparent and coloured hairs.

Microsporophylls: spirally orthostichous, aggregated into stalked male cones and each with a simple sterile apex, which is flattened or faceted, weakly bilobed, never produced into an upturned spine. Each microsporophyll bearing numerous microsporangia (pollensacs) on the abaxial surfaces. Microsporangia opening by slits. Pollen cymbiform, monosulcate.

Megasporophylls: spirally orthostichous, aggregated into stalked female cones. Sporophylls simple, appearing peltate with a simple dilated apex which is hexagonal, flattened or faceted, weakly bilobed, never produced into an upturned spine. 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 red, or pink 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.

The Cycad Pages
� 1998 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill
Please send comments and corrections