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:
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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. To refine a query, use the BACK button of your browser, return to the original query, and gradually add more characters.
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