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The Cycad Pages
Cycas brunnea

Cycas brunnea K.D. Hill, "Telopea 5(1): 200-201, fig. 15." (1992). H—DNA
"TYPE: Australia, Queensland, Burke District, Running Waters, Lawn Hill Creek (18°43'S 138°28'S, Maconochie 1661, 16 Nov 1972 (holo DNA, iso BRI, K)."


Etymology: From the late Latin brunneus, brown, in reference to the brown trichomes on new growth that distinguish this from related taxa.

Illustration: Hill 1992, fig. 15.

Distinguishing features: Distinguished from other Australian species by the relatively broad bluish leaflets with slightly recurved to almost flat margins on openly keeled leaves, the dark brown trichomes on new growth, and the large, strongly glaucous seeds. Most similar to C. angulata in habit, the large seeds, the dark brown tomentum, the large, subglobular male cone, and the regularly finely dentate megasporophyll lamina, but distinguished from that species by the broader, flatter leaflets (margins less recurved) which are more widely spaced on the rachis, the generally more strongly glaucous leaves and seeds, and the smaller seeds.

Distribution and habitat: Known from several populations in the headwaters of Lawn Hill Creek and its tributaries in Queensland, and on Wollogorang station in the Northern Territory. The Lawn Hill Creek occurrence is on limestone or alluvium derived from limestone, in exposed situations along small, open creek valleys. The Wollogorang occurrences are small relictual stands in sandy alluvium in gorges in siliceous sandstone.

Conservation status: Although restricted, several of the known populations are large and not under substantial threat, and are conserved in National Parks. 1997 IUCN Red List of Threatened Plants category R. ROTAP category 3RC.

Description:

Stems arborescent, to 2(-5) m tall, 17-23 cm diam. at narrowest point.

Leaves grey-green or blue, dull, 120-170 cm long, moderately keeled (opposing leaflets inserted at 90-135° on rachis), with 160-240 leaflets, with brown tomentum shedding as leaf expands; rachis usually terminated by a spine 5-10 mm long. Petiole 28-60 cm long, glabrous or pubescent, spinescent or unarmed (rarely), for 20-50% of length. Basal leaflets not gradually reducing to spines.

Median leaflets simple, weakly discolorous, 170-270 mm long, 6-7.5 mm wide, inserted at 40-50° to rachis, decurrent for 2-6 mm, narrowed to 4-5 mm at base (to 55-75% of maximum width), 9-13 mm apart on rachis; median leaflets section slightly keeled; margins slightly recurved; apex aristate, spinescent; midrib flat above, raised below.

Cataphylls linear, pungent, pilose, persistent.

Pollen cones globose, yellow, 21 cm long, 13 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 50-55 mm long, 20 mm wide, fertile zone 40 mm long, sterile apex 15 mm long, level, apical spine prominent, sharply upturned, 28 mm long.

Megasporophylls 28-32 cm long, brown-tomentose; ovules 4-6, glabrous; lamina lanceolate, 45-80 mm long, 18-22 mm wide, regularly dentate, with 24-30 pungent lateral spines 0.5-2 mm long, 1 mm wide, apical spine distinct from lateral spines, 16-32 mm long.

Seeds flattened-ovoid, 36-39 mm long, 28-32 mm wide; sarcotesta orange-brown, strongly pruinose, 2-4 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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