Illustration: Hill 1992, fig. 1. Historical notes: This species was discovered only in 1986 and named in 1992. Distinguishing features: Distinguished from other Australian species by the broader and relatively thinner adult leaflets. A striking qualitative distinction is the smooth trunk, resulting from the shedding of leaf bases and cataphylls more than about 4 years old. These organs are retained throughout in C. media and other related species. The broad, falcate leaflets and the non-pectinate megasporophyll apex with a distinct apical spine are similar to those of the complex surrounding C. rumphii Miq., which comprises about 12 taxa ranging from Sri Lanka and East Africa to Fiji and Tonga. Seeds, however, lack the spongy layer present in the C. rumphii complex (Dehgan & Yuen 1983, Hill 1994). C. silvestris also differs from superficially similar taxa on South Pacific Islands (C. seemannii A. Br.) in the strongly spinose petiole (the Pacific Island plants have no or rarely few spines on petioles) and the markedly smaller seeds. Two taxa in the C. rumphii group are known from Papua New Guinea (Hill 1994), all of which differ from C. silvestris in the large seeds with spongy endocarp. Early reports of C. rumphii from Queensland refer to C. silvestris (Bailey 1913). Distribution and habitat: C. silvestris is known only from subcoastal forests near the north-eastern tip of Cape York Peninsula, near Temple Bay and to the north and south of the Olive River estuary. These quite rich and complex rainforests and Melaleuca-dominated forests occur on white siliceous sands from old beach-dunes, and this cycad appears to be endemic to that substrate. Conservation status: This taxon is known from a few small stands that are not adequately reserved. 1997 IUCN Red List of Threatened Plants category V. ROTAP category 2V-.
Description:
Stems arborescent, to 3(-4) m tall, 10-15 cm diam. at narrowest point. Leaves bright green or deep green, highly glossy, 100-200 cm long, flat (not keeled) in section (opposing leaflets inserted at 180° on rachis), with 90-200 leaflets, with orange tomentum shedding as leaf expands; terminated by paired leaflets or a spine 1.5-10 mm long. Petiole 30-50 cm long (15-25% of total leaf), petiole glabrous, spinescent for 10-90% of length. Basal leaflets not gradually reducing to spines, 170-340 mm long. Median leaflets simple, strongly discolorous, 150-370 mm long, 9-15 mm wide, inserted at 45-60° to rachis, decurrent for 5-10 mm, narrowed to 3.5-5 mm at base (to 25-40% of maximum width), 11-17 mm apart on rachis; median leaflets section flat; margins slightly recurved; apex aristate, not spinescent; midrib flat above, raised below. Cataphylls linear, pungent, 130 mm long, articulated. Pollen cones narrowly ovoid, orange to brown, 11-22 cm long, 5-7 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 20-25 mm long, 11-13 mm wide, fertile zone 16-18 mm long, sterile apex 4-6 mm long, level, apical spine prominent, sharply upturned, 5-15 mm long. Megasporophylls 25-38 cm long, brown-tomentose; ovules 2-10, glabrous; lamina lanceolate, 30-85 mm long, 15-45 mm wide, regularly dentate, with 20-36 pungent lateral spines 2-4 mm long, 1-2 mm wide, apical spine distinct from lateral spines, 8-26 mm long. Seeds flattened-ovoid, 30-35 mm long, 25-30 mm wide; sarcotesta orange-brown, not pruinose, 1.5-2 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.
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