Illustration: Hill 1996, fig. 8. Historical notes: ALthough abundant along the only road through this region, this species was poorly collected and confused with C. media until 1994. Distinguishing features: Distinguished from other Australian species by the bright green, keeled leaves with keeled and usually falcate leaflets, the short, soft cataphylls, and the thick crown of orange wool around the cataphylls. The closely allied C. badensis differs in having a smaller megasporophyll apex with fewer and shorter lateral spines and a shorter terminal spine, somewhat less orange wool in the crown, and leaflets that are usually straight rather than falcate. C. campestris from New Guinea has similar keeled leaflets, but also rarely falcate, and with narrower bases. The latter species is also distinguished by the broader megasporophyll lamina with longer lateral teeth (see Hill 1994). The orange wool around the cataphylls is not present in most other species in this group, but occurs in a number of other more distantly related species such as C. cairnsiana, C. ophiolitica, C. maconochiei and C. lane-poolei. Distribution: Extremely abundant in northern Cape York Peninsula in an apparently very localised within an area lying to the north of the Wenlock River. A small disjunct population of somewhat more robust plants occurs on quartzite hills near Cape Melville. A single specimen apparently from Rokeby (Gordon s.n.) belongs to this species, although this would be from within the range of C. xipholepis. C. yorkiana usually occurs as an understorey plant in open Eucalyptus miniata -- E. tetrodonta forest on flat country, on sandy soils over laterite, although the Cape Melville population is on stony quartzite hills. Conservation status: Abundant but localised, not considered to be at risk.
Description:
Stems arborescent, to 4 m tall. Leaves bright green, semiglossy, 90-140 cm long, slightly keeled to flat (not keeled) in section (opposing leaflets inserted at 150-180° on rachis), with 160-220 leaflets, with orange tomentum shedding as leaf expands; rachis consistently terminated by a spine 5-20 mm long. Petiole 17-28 cm long (15-25% of total leaf), petiole glabrous or pubescent, spinescent for 5-90% of length. Basal leaflets not gradually reducing to spines, 30-50 mm long. Median leaflets simple, strongly discolorous, 140-190 mm long, 5.5-7.5 mm wide, inserted at 60-75° to rachis, decurrent for 3-5 mm, narrowed to 4-5 mm at base (to 55-80% of maximum width), 9-11 mm apart on rachis; median leaflets section slightly keeled; margins slightly recurved; apex acute, spinescent; midrib flat above, raised below. Cataphylls narrowly triangular, soft, densely floccose, 60-80 mm long, persistent. Pollen cones not seen, orange or brown, 8.5 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 35 mm long, 12 mm wide, apical spine 6 mm long. Megasporophylls 21-32 cm long, grey-tomentose; ovules 2-6, glabrous; lamina lanceolate, 60-100 mm long, 17-32 mm wide, regularly dentate, with 24-32 pungent lateral spines 3-6 mm long, 1-2 mm wide, apical spine distinct from lateral spines, 12-16 mm long. Seeds flattened-ovoid, 34 mm long, 30 mm wide; sarcotesta orange-brown, not pruinose, 4 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.
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