Photo Ken Hill
The Cycad Pages
Cycas cairnsiana

Cycas cairnsiana F. Muell., "Fragm. 10: 63, 121" (1876).
"TYPE: Australia, ""Ad montes Newcastle-Range"", Armit s.n. (holo MEL 68032)."

Photo Ken Hill
Etymology: Honouring -- Cairns, --

Illustration: Hill 1992, fig. 11.

Historical notes: Although described in 18--, this species hsa not been well understood. The type locality remained unknown for many years, and the name became misapplied to plants from a different locality (now C. platyphylla). With the discovery of the original site in the 1970's, this misunderstanding eventually became resolved in 1992. 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 this name.

Distinguishing features: Distinguished from other Australian species by the dense but very loose orange tomentum on new growth, the glabrous, strongly waxy and very glaucous mature leaves and seeds, and the very narrow leaflets with strongly recurved margins. Cataphylls are also short, soft and densely orange-floccose.

Distribution and habitat: Known from only two rather extensive and scattered populations about the Newcastle Range in the drier country of north-eastern Queensland, on shallow to skeletal gritty soils over siliceous granites. Plants from the population near Forsayth have slightly wider leaflets than those from near Mt Surprise.

Conservation status: Although both known populations are large, neither area is conserved and the striking appearance of this plant places it under considerable long-term threat from commercial collectors. 1997 IUCN Red List of Threatened Plants category V. ROTAP category 2V-.
Photo Ken Hill
Photo Ken Hill


Stems arborescent, to 2(-5) m tall, 12-16 cm diam. at narrowest point.

Leaves blue, dull, 60-110 cm long, strongly keeled (opposing leaflets inserted at 30-90° on rachis), with 180-220 leaflets, with orange tomentum shedding as leaf expands; rachis usually terminated by paired leaflets. Petiole 18-27 cm long, glabrous, spinescent for 30-100% of length. Basal leaflets not gradually reducing to spines.

Median leaflets simple, strongly discolorous, 80-180 mm long, 2-3(-4) mm wide, inserted at 20-60° to rachis, decurrent for 2-3 mm, narrowed to 2-3 mm at base (to 80-100% of maximum width), 5-6 mm apart on rachis; median leaflets section slightly keeled; margins revolute; apex aristate, spinescent; midrib flat above, raised below.

Cataphylls linear, soft, densely floccose, persistent.

Pollen cones ovoid, orange, 16-20 cm long, 7-10 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 35-50 mm long, 12-15 mm wide, fertile zone 22-34 mm long, sterile apex 12-15 mm long, deflexed, apical spine prominent, sharply upturned, 6-9 mm long.

Megasporophylls 16-21 cm long, brown-tomentose; ovules 2-4, glabrous; lamina lanceolate, 40-70 mm long, 15-25 mm wide, obscurely or regularly dentate, with 26-32 pungent lateral spines 0-1 mm long, 1 mm wide, apical spine distinct from lateral spines, 15-20 mm long.

Seeds flattened-ovoid, 36-42 mm long, 30-37 mm wide; sarcotesta orange-brown, strongly pruinose, 3-4 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.

The Cycad Pages

© 1998-2012 Royal Botanic Gardens Sy dney
Written and maintained by Ken Hill 1998-2010
Maintained by Leonie Stanberg and Dennis Stevenson 2010-2012
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