Etymology:
From the Greek platys, broad, and phyllon, leaf,
in reference to the broad sterile tip of the megasporophyll.
Illustration: Hill 1992, fig. 9. Historical notes: The name C. cairnsiana has been misapplied to this taxon by botanists and growers alike. The type locality of C. cairnsiana was unknown for a long period, but has been recently rediscovered, allowing clarification of application of the name. Distinguishing features: Distinguished from other Australian species by the initially bluish leaves becoming yellowish green, the moderately broad leaflets with recurved margins, the thick orange tomentum around the soft cataphylls, and the broad lamina of the megasporophylls. Distribution and habitat: Known from the Petford district on the north-western Atherton Tableland, and a disjunct population about 250 km to the south on Wandovale station. In both localities, it occurs in open grassy ironbark-dominated woodland on shallow loamy soils on stony slopes over acid to intermediate volcanics. An extensive and variable population in the Irvinebank-Ravenshoe-Mt. Garnet district on the western Atherton Tableland is intermediate in all respects between C. platyphylla and C. media. This occurrence is regarded as a highly variable breeding population that was originally of hybrid origin between these two taxa, but would now have limited scope for genetic interchange with the parent species. Conservation status: The range of this species is small, and none of the habitat is conserved. The species is also under some threat from collectors. 1997 IUCN Red List of Threatened Plants category V. ROTAP category 2V-.
Description:
Stems arborescent, to 2(-4) m tall, 10-15 cm diam. at narrowest point. Leaves deep green or grey-green (blue wnen new), highly glossy or semiglossy, 55-111 cm long, strongly keeled (opposing leaflets inserted at 45-60° on rachis), with 120-260 leaflets, with orange tomentum shedding as leaf expands; rachis usually terminated by a spine. Petiole 12-24 cm long, glabrous, spinescent for 60-100% of length. Basal leaflets not gradually reducing to spines. Median leaflets simple, strongly discolorous, 90-170 mm long, 4-6 mm wide, inserted at 45-60° to rachis, decurrent for 2-4 mm, narrowed to 3-4 mm at base (to 65-85% of maximum width), 5-10 mm apart on rachis; median leaflets section flat, or slightly keeled; margins recurved; apex aristate, spinescent; midrib flat above, raised below. Cataphylls linear, soft, densely floccose, persistent. Pollen cones ovoid, orange, 15-20 cm long, 8-11 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 30-35 mm long, 9-13 mm wide, fertile zone 22-26 mm long, sterile apex 7-10 mm long, deflexed, apical spine prominent, sharply upturned, 6-9 mm long. Megasporophylls 16-32 cm long, brown-tomentose; ovules 4-6, glabrous; lamina ovate to lanceolate, 50-80 mm long, 16-37 mm wide, regularly dentate, with 30-36 pungent lateral spines 0.5-2 mm long, 1 mm wide, apical spine distinct from lateral spines, 20-25 mm long. Seeds flattened-ovoid, 30-40 mm long, 27-38 mm wide; sarcotesta orange-brown, strongly pruinose, 3-4 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.
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