K.D. Hill
Encephalartos Lehm., Pugill. 6: 14 (1834);
from the Greek
en, in,
cephale, head, and
artos, bread,
in reference to the flour
obtained from the trunks of some species by the indigeous tribespeople.
Type:
Encephalartos friderici-guilielmi Lehm.
Named by German botanist J.G.C. (Johann Georg Christian) Lehmann in 1834. All cycads except
Cycas
had been regarded as members of the genus
Zamia until then, and some botanists
continued to follow this line for many years after Lehmann had separated
Encephalartos as a separate genus. His concept was originally
much broader than ours today,
including also the Australian plants we now know as
Macrozamia and
Lepidozamia.
Zamiaceae; 62 species, Africa.
Distinguishing characters:
- Leaves pinnate
- Leaflets lacking a midrib
- Leaflets not articulated
- Sporophylls not in vertical rows in cones
- Megasporophyll apices faceted or flattened and deflexed
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Description:
Habit: dioecious palmlike shrubs with often large aerial or subterranean,
pachycaul, cylindrical stems, with usually many leaves and persistent leaf bases. Basal offsets ("suckers")
produced by most species, aerial branching uncommon.
Leaves: pinnate, spirally arranged, interspersed with cataphylls,
lower leaflets often reduced to spines. Petioles lacking prickles, usually swollen at the base,
with a distinctly differently coloured collar in some species. Longitudinal ptyxis erect,
horizontal ptyxis erect. Leaflets simple, frequently with spiny, dentate or lobed
margins, with numerous bifurcating parallel
veins and no distinct midrib, leaflets not 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 or simple transparent hairs.
Microsporophylls: spirally aggregated into determinate, stalked or sessile
male cones and each with a simple sterile apex, which is often
flattened or faceted but never produced into an upturned spine. Each microsporophyll bearing
numerous microsporangia (pollensacs) on its abaxial surfaces.
Microsporangia opening by slits. Pollen cymbiform, monosulcate.
Megasporophylls: spirally aggregated into determinate, stalked
female cones. Sporophylls simple, appearing peltate with a simple
dilated apex which is often flattened or faceted but 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,
yellow, orange or brown 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 a more traditional
dichotomous key under development, but not yet ready.
To use this key, start with one or two characters that are clear.
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return to the original query, and gradually add more characters.
The Cycad Pages
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© 1998-2012 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill 1998-2010
Maintained by Leonie Stanberg and Dennis Stevenson 2010-2012
This site is currently not being maintained
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