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The Cycad Pages
Cycas conferta

Cycas conferta Chirgwin ex Chirgwin & Wigston, J. Adelaide Bot. Gard. 15(2): 147 (1993). H—DNA
"TYPE: Australia, Northern Territory, G. Brown DNA 29214, 21 April 1987, female plant (holo DNA; iso NSW)."


Etymology: From the Latin confertus, crowded, referring to the close crowding of the leaflets on the rachis.

Illustration: Hill 1996, fig. 16.

Distinguishing features: Distinguished by the dull, pale green and usually very slightly bluish leaves with relatively long and usually unarmed petioles and broad, closely crowded, concolorous and often partly amphistomatic leaflets. C. armstrongii has been confused with this species, but differs in the shorter, more frequently spinescent petioles and the glossy, discolorous and more widely spaced leaflets. The habit of C. armstrongii is also smaller. C. papuana from the Western District of Papua New Guinea shares the long petioles and crowded, concolorous leaflets, but has more robust male cones with elongated, decurved sterile apices on the male sporophylls.

Distribution and habitat: A somewhat restricted species, usually occurring on sandy soils over granites or coarse sandstones. Sporadic and local in occurrence, forming isolated, usually small but dense, stands from Kakadu National Park (near Twin Falls and Goodparla homestead) to west of Pine Creek. Populations at Mt Bundey and near Hayes Creek are intermediate between C. conferta and C. armstrongii, and those at Goodparla show slight C. armstrongii influence. Apparent hybrids with C. calcicola are also known.

Conservation status: Populations are small and localised, and under some threat from collectors. Regeneration is also threatened by frequent fires and, to a lesser extent, seed collectors, even though some stands are conserved within Kakadu National Park. 1997 IUCN Red List of Threatened Plants category V. ROTAP category 2VC-.

Description:

Stems arborescent, to 4(-7) m tall, 9-13 cm diam. at narrowest point.

Leaves bright green (slightly bluish), dull, 70-110 cm long, slightly keeled to flat (not keeled) in section (opposing leaflets inserted at 130-180° on rachis), with 160-240 leaflets, with white and orange tomentum shedding as leaf expands; rachis consistently terminated by a spine (sometimes toothed). Petiole 20-45 cm long, glabrous (or loosely pubescent), unarmed. Basal leaflets not gradually reducing to spines.

Median leaflets simple, concolorous (someties party amphistomatic), 70-120 mm long, 6-8 mm wide, inserted at 60-90° to rachis, decurrent for 1-2 mm, narrowed to 3.5-5.5 mm at base (to 60-80% of maximum width), 5-8 mm apart on rachis; median leaflets section flat; margins flat; apex acute, not spinescent; midrib raised above, raised below.

Cataphylls linear, pungent, pilose, 60-90 mm long, persistent.

Pollen cones ovoid, orange, 11-18 cm long, 8-12 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 25-29 mm long, 14-17 mm wide, fertile zone 19-24 mm long, sterile apex 5-9 mm long, level, apical spine prominent, sharply upturned, 7-11 mm long.

Megasporophylls 17-22 cm long, grey-tomentose and brown-tomentose; ovules 2-4, glabrous; lamina lanceolate, 45-75 mm long, 18-30 mm wide, regularly dentate, with 18-24 pungent lateral spines 1-3 mm long, 1 mm wide, apical spine distinct from lateral spines, 8 mm long, 2-4 mm wide at base.

Seeds flattened-ovoid to oblong, 40 mm long, 30 mm wide; sarcotesta orange-brown, slightly pruinose, 2-3 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.


The Cycad Pages

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Written and maintained by Ken Hill 1998-2010
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