Photo Ken Hill
logo
The Cycad Pages
Cycas diannanensis

Cycas diannanensis Z.T. Guan & G.D. Tao, "Sichuan Forestry & Desig, 1995: 1" (1995).
"TYPE: China, Yunnan, S. Gejiu County, Manhao, alt 700-1120 m., G.D. Tao 95014 (holo I??)."


Etymology: From the municipality of Diannan in Gejiu County, Yunnan Province.

Literature: Wang 1996, and as C. parvulus.

Illustrations: Wang 1996, and as C. parvulus.

Historical notes: Although spread over a wide area and in parts once abundant in the Red River valley, this species remained undetected until the 1990's. Curiously, it was then separately described by three different groups of botanists working independently.

Distinguishing features: Within the group of Chinese cycads with soft pollen cones, loose, freely peeling sarcotesta lacking a fibrous layer and rugose sculpting of the sclerotesta (Section Stangerioides), C. diannanensis is distinguished by its long, prominent and pungent cataphylls, and also by the small seeds, broad leaflets with flat or undulate margins, leaflets that are flat and not twisted on the rachis, and a large megasporophyll apex with a broad apical spine.

Distribution and habitat: A widespread species through central and eastern Yunnan, along the Hong He valley between Hekou and Shuangbai. This species occurs on a range of substrates from limestone to shale and schist, usually on steep slopes high on ridges, between about 600 and 1800 m. Original vegetation was closed evergreen forest in the cloud zone, although today it is often severely degraded to grassland or scrubby secondary regrowth.

Conservation status: Widespread across a range of several hundred kilometers, and present good populations in a number of natural reserves. Although depleted in numbers in recent times, this species is not considered to be seriously at risk. IUCN (1994) status LR, cd.
Photo Ken Hill
Photo Ken Hill

Description:

Stems arborescent or acaulescent, to 3 m tall, 25-35 cm diam. at narrowest point; 12-50 leaves in crown.

Leaves bright green or deep green, highly glossy, 140-330 cm long, slightly keeled or flat (not keeled) in section (opposing leaflets inserted at 160-180° on rachis), with 160-300 leaflets, with white or orange tomentum shedding as leaf expands; rachis usually terminated by a spine or paired leaflets; 1-11 mm long. Petiole 45-100 cm long (20-30% of total leaf), petiole glabrous, spinescent for 90-100% of length. Basal leaflets not gradually reducing to spines, 30-240 mm long.

Median leaflets simple, strongly discolorous, 130-320 mm long, 9-16 mm wide, inserted at 50-80° to rachis, decurrent for 3-7 mm, narrowed to 2.5-4 mm at base (to 20-30% of maximum width), 10-20 mm apart on rachis; median leaflets section flat; margins slightly recurved; apex acute, not spinescent; midrib raised above, raised below.

Cataphylls linear, pungent, thinly sericeous or lacking tomentum, 120-200 mm long, persistent.

Pollen cones narrowly ovoid, yellow, 50-65 cm long, 9-13 cm diam.; microsporophyll lamina soft, not dorsiventrally thickened, 35-60 mm long, 15-25 mm wide, fertile zone 30-50 mm long, sterile apex 4-10 mm long, raised, apical spine rudimentary, sharply upturned, 0-2 mm long.

Megasporophylls 16-24 cm long, grey-tomentose; ovules 4-8, glabrous; lamina orbicular or ovate, 65-140 mm long, 55-140 mm wide, deeply pectinate, with 30-52 soft lateral spines 10-50 mm long, 1.5-4 mm wide, apical spine distinct from lateral spines, 10-45 mm long, 7-15 mm wide at base.

Seeds ovoid, 28-40 mm long, 20-32 mm wide; sarcotesta yellow, not pruinose, 3-4 mm thick; fibrous layer absent; sclerotesta verrucose. Spongy endocarp absent.


The Cycad Pages

© 1998-2012 Royal Botanic Gardens Sydney
Written and maintained by Ken Hill 1998-2010
Maintained by Leonie Stanberg and Dennis Stevenson 2010-2012
This site is currently not being maintained