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The Cycad Pages
Cycas maconochiei

Cycas maconochiei Chirgwin & K.D. Hill, "Telopea 7(1): 48-49, fig. 22" (1996). H—NSW
"TYPE: Australia, Northern Territory, Mandorah road, at Bynoe Harbour turnoff, K.D. Hill 4461 & H.M. Anderson, 4 Sep 1993 (holo NSW; iso DNA, PE, NY)"[NSW][NSW]


Etymology: Honouring the late John Maconochie, formerly botanist with the Northern Territory government, who had commenced a major revision of the genus Cycas. His work was tragically curtailed, but his notes and specimens remained, and have been invaluable in this work.

Distinguishing features: distinguished by the flattened leaves with short petioles and leaflets with recurved margins, and the basal leaflets reducing in size. Distinguished from C. arnhemica by the abundant orange-brown tomentum around the cataphylls.

Distribution: this taxon occurs in the north-west of the Northern Territory, with one population in the Cox Peninsula area west of Darwin, and a very large disjunct occurrence south of the Daly River and towards the coast.

Three geographically separated occurrence are recognised as subspecies.

Key to the subspecies.

1 leaflets dull bluish green, usually retaining some tomentum

 2 leaflets 5.5--7.0 mm wide, flat, margins slightly recurved, spaced at 8--10 mm on rachis -- A. subsp. maconochiei

 2* leaflets 3.5--5.5 mm wide, somewhat keeled, margins strongly recurved, spaced at 5--7 mm on rachis -- B. subsp. lanatus

1* leaflets glossy mid-green, becoming glabrous when older -- C. subsp. viridis

A. Cycas maconochiei subsp. maconochiei

Distribution: subsp. maconochiei is restricted to a small area between Fog Bay and Port Darwin, to the south-west of Darwin. It occurs in open savanna forests on flat sites dominated by Eucalyptus miniata and E. tetrodonta on sandy soil over Tertiary laterites. Apparent hybrids are known with C. armstrongii.

Conservation status: locally extremely abundant, not considered to be at risk. Although not reserved, the extreme abundance of this species would buffer it from any threat in the medium term. Seed and plant collectors may pose a problem in the future, in particular when frequent fire also effectively blocks reproduction and uncontrolled development alienates significant proportions of the habitat.

B. Cycas maconochiei subsp. lanata

Distinguished by the narrow leaflets with more strongly recurved margins, and the thickly woolly cataphylls. Subsp. maconochiei from farther north differs in the broader, flatter and more widely spaced leaflets, and the somewhat less densely tomentose cataphylls, and subsp. viridis from farther west has broader leaflets that are glossy green. Both subsp. maconochiei and subsp. lanatus have a more or less persistent indumentum on the leaves, that of subsp. maconochiei is usually light orange-brown or even paler, whereas that of subsp. lanata is a darker red-brown. Tomentum is less persistent and eventually lost in subsp. viridis. Subsp. lanatus varies markedly in stature across its range, in particular in that plants from the north-west of the range (around Nardirri) are consistently very much smaller, although similar in all other attributes.

Distribution: widespread and in parts extremely abundant, usually on sandy soils. Known only from the northern Wingate Mountains and adjacent plains country to the north and west, extending to the coast north of Peppimenarti, and west almost to Port Keats. Initial estimates suggest that the total population of this subspecies would number into the tens of millions.

Conservation status: abundant and widespread, not considered to be at risk. Although not reserved, the extreme abundance of this species would buffer it from any threat in the medium term. Almost all populations are on aboriginal land, and conservation issues on such land are yet to be fully addressed. The inhibition of reproduction by too-frequent fire is one such issue.

Etymology: the epithet is from the Latin lanatus, woolly, in reference to the densely tomentose cataphylls.

C. Cycas maconochiei subsp. viridis

Distinguished by the relatively broad, glossy green leaflets with recurved margins, and the thickly woolly cataphylls. Subsp. maconochiei from some distance farther north differs in the dull, flatter and more widely spaced leaflets, and the less densely tomentose cataphylls. Subsp. lanatus, adjacent to the north and east, has narrower, dull leaflets.

Distribution: scattered and locally abundant, usually on sandy soils or on old beach sands. Known only from around Fossil Head.

Conservation status: not considered to be at risk. Although not reserved, the remote occurrence of this subspecies would buffer it from any threat in the medium term. All populations are on aboriginal land, and conservation issues on such land are yet to be fully addressed. The inhibition of reproduction by too-frequent fire is one such issue.

Etymology: The epithet is from the Latin viridis, green, in reference to the bright green leaves.

Description:

Stems arborescent, to 3(-7) m tall, 9-15 cm diam. at narrowest point.

Leaves deep green or grey-green, semiglossy, 70-120 cm long, slightly keeled (opposing leaflets inserted at 130-160° on rachis), with 140-230 leaflets, with white and orange tomentum shedding as leaf expands or persistent above and below; rachis usually terminated by a spine. Petiole 18-33 cm long, glabrous or pubescent, unarmed or spinescent for 0-100% of length. Basal leaflets gradually reducing to spines.

Median leaflets simple, strongly discolorous, 70-150 mm long, 3.5-7 mm wide, inserted at 60-90° to rachis, decurrent for 1.5-3 mm, narrowed to 2.5-4.5 mm at base (to 55-80% of maximum width), 5-10 mm apart on rachis; median leaflets section flat, or slightly keeled; margins slightly recurved, or recurved; apex aristate, spinescent; midrib flat above (or slightly raised), raised below.

Cataphylls linear, soft, densely floccose, 60-80 mm long, persistent.

Pollen cones narrowly ovoid, orange, 20-34 cm long, 10-14 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 25-35 mm long, 9-12 mm wide, fertile zone 20-27 mm long, sterile apex 5-8 mm long, level, apical spine prominent, sharply upturned, 4-8 mm long.

Megasporophylls 20-27 cm long, grey-tomentose and brown-tomentose; ovules 2-4, glabrous; lamina lanceolate, 40-60 mm long, 14-22 mm wide, regularly dentate, with 24-36 pungent lateral spines 1-4 mm long, 1 mm wide, apical spine distinct from lateral spines, 10 mm long.

Seeds flattened-ovoid, 33-36 mm long, 29-32 mm wide; sarcotesta orange-brown, slightly pruinose, 3 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.


The Cycad Pages

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Written and maintained by Ken Hill 1998-2010
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