||Photo Dennis Stevenson|
Microcycas (Miq.) A. DC., Prodr. 16(2): 522-548 (1868);
from the Greek micro small, and the generic name Cycas,
i.e. a small Cycas. Type: Microcycas calocoma (Miq.) A. DC.
A genus of one species,
in the family Zamiaceae.
Endemic in Cuba.
- Leaves pinnate
- Leaflets lacking a midrib
- Leaflets articulated
- Sporophylls in vertical rows in cones
- Megasporophyll apices faceted or flattened, bilobed
Habit: dioecious palm-like shrubs with tall aerial,
pachycaul, cylindrical stems, with many leaves.
Leaf bases persistent. New leaves emerging in flushes, with distinctly apparently truncate apices.
Dichotomous branching uncommon,
basal offsets ("suckers") produced ocasionally.
Leaves: pinnate, spirally arranged, interspersed with cataphylls,
lower leaflets not reduced to spines. Petioles lacking 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 branched and simple, transparent and coloured hairs.
Microsporophylls: spirally orthostichous, aggregated into sessile
male cones and each with a simple sterile apex, which is often
flattened or faceted, bilobed, never produced into an
upturned spine. Each microsporophyll bearing
numerous microsporangia (pollen-sacs) on the abaxial surfaces.
Microsporangia opening by slits. Pollen cymbiform, monosulcate.
Megasporophylls: spirally orthostichous, aggregated into sessile
female cones. Sporophylls simple, appearing peltate with a simple
dilated apex which is usually hexagonal, flattened or faceted,
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,
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