The Cycad Pages
Cycas aculeata

Cycas aculeata K.D. Hill & H.T. Nguyen , Bot. Rev. 70(2): 149-150 (2004). H—HN
"TYPE: Vietnam: Thua Thien - Hue: Phu Loc, Hai Van pass, lower on southern side, T.H. Nguyen 4156 & K.D. Hill, 23 Jan 2000 (holo HN, iso NSW)."

Etymology: From the Latin aculeatus, prickly, in reference to the prominent spines on the petiole.

Historical notes: Discovered and recognised as a distinct species only in the late 1990's.

Distinguishing features: This species is one of the complex of closely related mostly acaulescent taxa that is distributed through northern Vietnam, Laos, northern Thailand and Yunnan and Guangxi in southern China (Section Stangerioides). It is distinguished by the few long leaves with long petioles bearing long slender spines and a light orange-brown tomentum. Microsporangiate cones are small in size with rounded microsporophylls which lack any apiculus. It is most similar to C. balansae, differing in the more numerous leaves with relatively longer petioles, the light orange-brown tomentum, the longer and wider, slightly keeled leaflets that are more narrowed at the base, and the longer cataphylls.

Distribution and habitat: Known at present from a single site on the southern slopes of the range at Hai Van pass, in dense bamboo, shrub and grass regrowth after forest clearing. Forests in the vicinity were severly affected by herbicide spraying during the north-south war in the early 1970's. It is locally frequent on loamy soils over granite on steep slopes, but the extent of the occurrence is unknown.

Conservation status: Although very poorly known to date, it is likely that this species is more widespread in the surrounding hills, IUCN (1994) Red List status DD, possibly VU.


Stems acaulescent, 15-18 cm diam. at narrowest point; 6-23 leaves in crown.

Leaves deep green, highly glossy or semiglossy, 180-250 cm long, slightly keeled (opposing leaflets inserted at 130-170° on rachis), with 100-150 leaflets, with orange tomentum shedding as leaf expands; rachis consistently terminated by paired leaflets. Petiole 60-110 cm long (35-50% of total leaf), petiole glabrous or pubescent, spinescent for 100% of length. Basal leaflets not gradually reducing to spines, 260-380 mm long.

Median leaflets simple, strongly discolorous, 350-520 mm long, 13-19 mm wide, inserted at 45-60° to rachis, decurrent for 4-6 mm, narrowed to 2-3 mm at base (to 10-20% of maximum width), 15-28 mm apart on rachis; median leaflets section slightly keeled; margins flat; apex softly acuminate, not spinescent; midrib raised above, flat below or raised below.

Cataphylls narrowly triangular, soft, pilose, 80-100 mm long, persistent.

Pollen cones narrowly ovoid or fusiform, 15-20 cm long, 4-6 cm diam.; microsporophyll lamina soft, not dorsiventrally thickened, 22-25 mm long, 12-14 mm wide, fertile zone 20-22 mm long, sterile apex 2-3 mm long, level, apical spine absent.

The Cycad Pages

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Written and maintained by Ken Hill 1998-2010
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