|Photo Ken Hill
|The Cycad Pages
- Cycas pruinosa Maconochie, "J. Adelaide Bot. Gard. 1(3): 177-178, fig. 2." (1978). H—NT
- "TYPE: Australia, Western Australia, Durack Ranges, Ternonis Gorge, Jun 1975, D. Symon s.n. (holo NT (2 sheets); iso BRI, CANB, K, L, NSW, PERTH)."[NSW]
From the Latin pruinosus, covered with a waxy whitish bloom.
Although strikingly distinctive and quite widespread,
this species was only first recognised
as recently as 1978 by Australian botanist
Distinguished by the narrow glabrous leaflets with strongly recurved
margins, the long, slender microsporangiate cones, and the long
megasporophylls with long sterile apices.
Glaucous leaf waxes may be either present or absent, causing plants
to be either blue or green in overall appearance. This is apparently
genetically controlled, different populations being completely
blue (eg. those at Lake Argyle and Bedford Downs), completely
green (eg. those at Deception Range) or mixed (eg. those at
Cycad Hill). A similar phenomenon occurs in C. furfuracea,
in that case the green plants being very much less common
and never occurring without the blue plants.
Distribution and habitat:
A widespread but sporadic species in the eastern and southern
Kimberley region of Western Australia, occurring also in the Spirit
Hills on Bullo River station in the Northern Territory. Found
on mainly skeletal sandy soils on siliceous substrates, from metasandstones
to granites. One occurrence in Western Australia is, however,
on red Terra Rosa soil on limestone (near Tunnel Creek, in the
Not considered to be at risk.
|Photo Ken Hill
|Photo Ken Hill
Stems arborescent, to 1.5(-2.5) m tall, 15-25(-35) cm diam. at narrowest point.
Leaves bright green or blue, semiglossy or dull, 60-125 cm long, strongly keeled (opposing leaflets inserted at 45-90° on rachis), with 130-320 leaflets, with white tomentum shedding as leaf expands; terminated by paired leaflets or a spine 1-4 mm long. Petiole 8-23 cm long, glabrous or pubescent, spinescent for 50-100% of length. Basal leaflets gradually reducing to spines.
Median leaflets simple, strongly discolorous, 110-170 mm long, 2.5-4 mm wide, inserted at 40-60° to rachis, decurrent for 2.5-4 mm, narrowed to 2-3 mm at base (to 80-100% of maximum width), 5-9 mm apart on rachis; median leaflets section slightly keeled; margins revolute; apex aristate, spinescent; midrib raised above, raised below (prominent).
Cataphylls linear, soft, pilose, 70 mm long, persistent.
Pollen cones fusiform, orange to brown, 35-45 cm long, 5-7 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 20-30 mm long, 8-13 mm wide, fertile zone 12-18 mm long, sterile apex 9-14 mm long, deflexed, apical spine prominent, sharply upturned, 6-25 mm long.
Megasporophylls 25-45 cm long, white-tomentose to grey-tomentose or brown-tomentose; ovules 2-6, glabrous; lamina lanceolate, 95-190 mm long, 18-40 mm wide, shallowly pectinate or regularly dentate, with 14-24 soft lateral spines 5-10 mm long, 2-3 mm wide, apical spine distinct from lateral spines, 10-45 mm long.
Seeds flattened-ovoid, 32-36 mm long, 28-32 mm wide; sarcotesta orange-brown, strongly pruinose, 2-3 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.