Photo Anders Lindstrom
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The Cycad Pages
Cycas debaoensis

Cycas debaoensis Y.C. Zhong & C.J. Chen, Acta Phytotax. Sin. 35(6): 571 (1997). H—PE
"TYPE: China, Guangxi, Debao, 106 14'E 23 30'N, 27 Aug 1997, Y.C. Zhong 8762 (holo PE iso GXF)."


Etymology: From the county of Debao in western Guangxi province, with the Latin termination -ensis, place of origin.

Historical notes: This remarkable species was only discovered in 1996 and described in 1998 by Chinese botanists C.J. Chen and Y.C. Zhong.

Distinguishing features: The bipinnate leaves immediately distinguish this species and the closely related C. multipinnata within the genus. C. debaoensis is distinguished from the latter by the shorter and more numerous leaves with narrower, thicker leaflets that are broadest below the mid-point, and the larger megasporophylls with longer teeth on the apical lamina. The subterranean habit, the small, soft microsporangiate cones, the loose, freely peeling sarcotesta lacking a fibrous layer and the verrucose sclerotesta are features shared by a wider group of related species (Section Stangerioides).

Distribution and habitat: Known from a limited area Debao County in western Guangxi, growing in mixed evergreen and deciduous woodland on limestone on slopes. Most of the forest habitat has been cleared or severely degraded.

Conservation status: This species is known only from a single small population that is already severely depleted from habitat destruction, and is now potentially at risk from horticultural collectors. IUCN (1994) Red List status CR B2.
Photo Ken Hill
Photo Ken Hill

Description:

Stems acaulescent, 15-20 cm diam. at narrowest point; 4-10 leaves in crown.

Leaves deep green, semiglossy, 250-300 cm long, moderately keeled (opposing leaflets inserted at 80° on rachis), with 30-50 leaflets, with white tomentum shedding as leaf expands; rachis consistently terminated by paired leaflets. Petiole 80-150 cm long (30-50% of total leaf), petiole glabrous, spinescent for 100% of length. Basal leaflets not gradually reducing to spines, 130-170 mm long.

Median leaflets dichotomously branched, strongly discolorous, 500-560 mm long, 7-11 mm wide, inserted at 75-80° to rachis, narrowed to 2-3 mm at base, 40 mm apart on rachis; median leaflets section flat; margins flat; apex acute, not spinescent; midrib raised above, flat below.

Cataphylls narrowly triangular, soft, pilose, 70-90 mm long, articulated.

Megasporophylls 12-14 cm long, brown-tomentose; ovules 2-6, glabrous; lamina orbicular or ovate, 80-90 mm long, 80-90 mm wide, deeply pectinate, with 26-28 soft lateral spines 40-50 mm long, 2 mm wide, apical spine distinct or not distinct from lateral spines, 30-40 mm long, 3-4 mm wide at base.

Seeds ovoid, 25-27 mm long, 20-22 mm wide; sarcotesta yellow, not pruinose, 2 mm thick; fibrous layer absent; sclerotesta verrucose. Spongy endocarp absent.


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Written and maintained by Ken Hill 1998-2010
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