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The Cycad Pages
Cycas pectinata

Cycas pectinata Buch.-Ham., "Mem. Wern. Nat. Hist. Soc. 5(2): 322-323, figs 3, 5" (1826).
TYPE: not known.

Cycas pectinata Griff., Not. Pl. Asiat. 4: 10 (1854).

"TYPE: Icones Plantarum Asiatarum 4: Plate 360, Fig. 3, 1854."


Etymology: Latin pectina, a comb, in reference to the long, comb-like teeth of the megasporophylls.

Literature: Kurz 1877, Leandri 1931, Schuster 1932, Ho & Duong 1960, Raizada & Sahni 1960, Suvatabandhu 1961, Smitinand 1971, Grierson & Long 1983, Wang 1996, Tang et al. 1997, Hill & Yang 1999.

Illustrations: Smitinand 1971, Cheng, Fu & Cheng 1975, Grierson & Long 1983, Wang 1996, Hill & Yang 1999.

Historical notes: Cycas pectinata was the fourth species of Cycas to be named, described in 1826 by Scottish surgeon and botanist Francis Buchanan-Hamilton (1762-1829), who worked as a surgeon in the Bengal medical service (1795-1815) and was superintendent of the Botanical Garden Calcutta (1814-1815). The type is not known. No type was cited, but reference was made to occurrence in "the hills which bound Bengal to the east", and the description cited "Habitat in Camrupae orientalis sylvis".

Cycas angulata R. Brown and Olus calappoides of Rumphius (C. rumphii) were cited (erroneously) in synonymy. The name has been attributed to Griffith, although he did not actually add his name to the binomial when describing it (Griffith's practice apparently was to add his name to new binomials, and place no name on existing or previously published binomials). Zhou et al. (1990) regarded Hamilton's publication as illegitimate because C. angulata was cited as a synonym. The latter was cited, but with a question mark, indicating that the author was unsure of the placement of C. angulata. This does not invalidate Hamilton's publication (see Greuter et el. 1990, Art. 63.1, note 1, example 6). The primary set of Hamilton's Bengal collections eventually went to Wallich and thence to Kew (K-W). A second set went to E. Neither set includes a specimen that could be regarded as the type of C. pectinata.

Distinguishing features: the very large, ovoid male cones with long, narrow microsporophylls, those with long apical spines, readily distinguish this species from others in the C. pectinata group. The group is distinguished by the broad, pectinate megasporophylls and the fibrous layer within the sarcotesta.

Distribution and habitat: Cycas pectinata is abundant in the hill forests of north-eastern India, and has also been collected from Nepal and Bhutan. It extends into northern Burma and Yunnan Province in southern China, and south and east into northern Thailand, Laos and Vietnam. This species occurs in medium to tall closed forest on deep, often clay-rich and more fertile soils, usually as part of the general shrub understorey in moderate to deep shade. C. pectinata is a plant of medium to higher elevations and moist conditions. It is recorded from a variety of substrates, but most frequently occurs on clay soils over limestone.

Conservation status: a widespread and locally abundant species. Although its habitat is continually being reduced, large populations remain, many in reserved areas in several different countries, and it is not under any immediate threat of extinction. IUCN (1994) Red List status VU A2c (on the basis of the continuing population decline, although the very large populations remaining indicate that the short-term threat of extinction is low).
Photo Ken Hill
Photo Ken Hill

Description:

Stems arborescent, to 1-12 m tall, 14-20 cm diam. at narrowest point; 30-40 leaves in crown.

Leaves deep green or grey-green, semiglossy, 150-240 cm long, flat (not keeled) in section (opposing leaflets inserted at 170-180° on rachis), with 180-312 leaflets, with white tomentum shedding as leaf expands; rachis consistently terminated by a spine 1-46 mm long. Petiole 30-80 cm long (25-50% of total leaf), petiole glabrous, spinescent for 30-80% of length. Basal leaflets not gradually reducing to spines, 50-160 mm long.

Median leaflets simple, strongly discolorous, 200-315 mm long, 7.5-10.5 mm wide, inserted at 45-60° to rachis, decurrent for 4-8 mm, narrowed to 2.5-4 mm at base (to 35-45% of maximum width), 8-13 mm apart on rachis; median leaflets section flat; margins slightly recurved; apex acute, spinescent to not spinescent; midrib raised above, raised below.

Cataphylls narrowly triangular, soft, pilose, articulated.

Pollen cones ovoid, yellow or green, 30-55 cm long, 16-22 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 43-60 mm long, 19-24 mm wide, fertile zone 35-57 mm long, sterile apex 3-8 mm long, level, apical spine prominent, sharply upturned, 17-32 mm long.

Megasporophylls 22-30 cm long, grey-tomentose; ovules 2-4, glabrous; lamina orbicular, 110-180 mm long, 100-130 mm wide, deeply pectinate, with 40-50 soft lateral spines 26-75 mm long, 2-3 mm wide, apical spine distinct from lateral spines, 35-75 mm long, 5-12 mm wide at base.

Seeds flattened-ovoid, 42-45 mm long, 33-45 mm wide; sarcotesta yellow, not pruinose, 4-7 mm thick; fibrous layer present; sclerotesta smooth. Spongy endocarp absent.


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Written and maintained by Ken Hill 1998-2010
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