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The Cycad Pages
Cycas hainanensis

Cycas hainanensis C.J. Chen, "Acta Phytotax. Sin. 13(4): 82, t. 2, figs 5-6" (1975).
"TYPE: Hainan: Luilianling, Wangning County, 16 Oct 1961, Y. Zhong 4706 (holo PE; iso IBSC)."


Etymology: From its natural occurrence in the island province of Hainan, with the Latin termination -ensis, place of origin.

Literature: Wang 1996 (as C. taiwaniana)

Illustrations: Cheng, Fu & Cheng 1975, Wang 1996 (as C. fairylakea and C. taiwaniana)

Historical notes: Described in 1975 by Chinese botanist C.J. Chen, from material collected by Y. Zhong in Wangning County in 1961. This species was initially contrasted with C. rumphii, although its affinities are now known to be quite removed from the latter. Chinese flora accounts recorded this species from only Hainan, although later accounts (Zhou et al. 1990) noted that it was cultivated in Fujian, Guangdong and Sichuan. More recently, a proposal was made that at least the Guangdong plants were taxonomically distinct (Deng, cited by Walters et al. 1995). We now know that the Mainland plants are distinct, and that the type of C. taiwaniana belongs here (see discussion under that species).

Distinguishing features: C. hainanensis is very close to C. taiwaniana, differing in the more keeled leaves with narrower and more crowded leaflets, and the smaller megasporophyll lamina with fewer but longer lateral spines and an often greatly expanded apical spine. Seeds are also distinctly larger.

Distribution and habitat: Known only from the wetter eastern parts of Hainan Island. Wild populations are now very restricted, and this species survives mainly in cultivation. Plants occur from sea level to about 1200 m. elevation, on soils on limestone and volcanic substrates. Climate here is subtropical, and rainfall high (c. 2000 mm annually), and the usual habitat is rainforest.

Conservation status: 1997 IUCN Red List of Threatened Plants category V.
Photo Ken Hill
Photo Ken Hill

Description:

Stems arborescent, to 0.3-1.5(-3.5) m tall, 30 cm diam. at narrowest point; 50-80 leaves in crown.

Leaves bright green, highly glossy, 70-230 cm long, moderately keeled (opposing leaflets inserted at 120-160° on rachis), with 100-280 leaflets, with orange tomentum shedding as leaf expands; rachis usually terminated by paired leaflets. Petiole 20-70 cm long (20-30% of total leaf), petiole glabrous, spinescent for 100% of length. Basal leaflets not gradually reducing to spines, 140 mm long.

Median leaflets simple, strongly discolorous, 150-300 mm long, 6-10 mm wide, inserted at 40-70° to rachis, decurrent for 2-7 mm, narrowed to 2.5-3 mm at base (to 30-45% of maximum width), 8-15 mm apart on rachis; median leaflets section slightly keeled; margins slightly recurved; apex acute, spinescent; midrib raised above, raised below (less prominently).

Cataphylls narrowly triangular, soft, pilose, 50-90 mm long, persistent.

Pollen cones fusiform, green or cream, 35-47 cm long, 10-12 cm diam.; microsporophyll lamina soft, not dorsiventrally thickened, 30-48 mm long, 20-30 mm wide, apex level, apical spine absent.

Megasporophylls 16-17 cm long, brown-tomentose; ovules 2-4, glabrous; lamina orbicular, 70-110 mm long, 40-60 mm wide, deeply pectinate, with 15-32 soft lateral spines 25-32 mm long, 2 mm wide, apical spine distinct from lateral spines, 20-30 mm long, 10-25 mm wide at base.

Seeds subglobose to ovoid, 35-40 mm long, 30-35 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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