Etymology: from the Latin collinus, pertaining to hills, from the occurrence at moderate to high elevations in mountainous country. Historical notes: Discovered and recognised as a distinct species only in the late 1990's. Distinguishing features: The few leaves with widely spaced leaflets, and the large male cones with rounded microsporophylls which lack any apiculus distinguish C. collina within a group of acaulescent taxa that have reduced megasporophylls lacking a clearly distinct apical spine. Distribution and habitat: Somewhat restricted in distribution, in mountainous regions mostly in Son La province in the north of Vietnam, above about 500 metres elevation, in evergreen or partly deciduous forests or woodlands or bamboo thickets on steep slopes of mountain ridges. Substrate varies from red clay soils on limestone to loamy soils on metasediments. This species would also be expected to occur in Laos. Conservation status: a widespread species, although not occurring in large or dense populations. Although its habitat is continually being reduced, many populations remain, and it is not under any immediate threat of extinction. IUCN (1994) status VU A2c.
Description:
Stems acaulescent, 10-14 cm diam. at narrowest point; 2-5 leaves in crown. Leaves deep green, semiglossy, 180-330 cm long, slightly keeled (opposing leaflets inserted at 150-170° on rachis), with 110-180 leaflets, with orange tomentum shedding as leaf expands; rachis usually terminated by paired leaflets. Petiole 70-190 cm long (40-55% of total leaf), petiole glabrous, spinescent for 90-100% of length. Basal leaflets not gradually reducing to spines, 200-260 mm long. Median leaflets simple, strongly discolorous, 280-410 mm long, 17-23 mm wide, inserted at 80-85° to rachis, decurrent for 2-5 mm, narrowed to 2.5-4 mm at base (to 10-25% of maximum width), 17-25 mm apart on rachis; median leaflets section flat, or slightly keeled; margins flat or undulate; apex softly acuminate, not spinescent; midrib raised above, raised below. Cataphylls narrowly triangular, soft, pilose, 50-80 mm long, persistent. Pollen cones narrowly ovoid or fusiform, yellow, 25-35 cm long, 7-9 cm diam.; microsporophyll lamina soft, not dorsiventrally thickened, apex level, apical spine absent. Megasporophylls 8-14 cm long, yellow-tomentose; ovules 2-4, glabrous; lamina ovate, 60 mm long, 30 mm wide, deeply pectinate, with 12 soft lateral spines 30 mm long, 2 mm wide, apical spine not distinct from lateral spines. Seeds ovoid; fibrous layer absent; sclerotesta verrucose. Spongy endocarp absent.
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