The Cycad Pages
Cycas micronesica

Cycas micronesica K.D. Hill, "Austral. Syst. Bot. 7: 554-556, fig 10" (1994). H—NSW
"TYPE: Guam, Anderson Air Force Base, T.L. Turner NSW 270411, 1992 (holo NSW; iso CANB, NY, K)."[NSW][NSW][NSW]

Etymology: From the endemic occurrence of this species in Micronesia.

Literature: Schuster 1932 (as C. rumphii), Kanehira 1938 (as C. rumphii), Stone 1970 (as C. circinalis), Fosberg & Sachet 1975 (as C. circinalis), Fosberg et al. 1982 (as C. circinalis).

Illustration: Hill 1994c, fig. 10.

Historical notes: Nomenclature of this taxon has been unstable, with the name C. circinalis L. frequently applied (Stone, 1970; Fosberg & Sachet, 1975; Fosberg et al., 1982). Schuster (1932) made the combination C. circinalis forma undulata, and included material from Micronesia thereunder (together with other clearly different material from Asia). Kanehira (1938) realised the affinities with C. rumphii, and corrected the error he had perceived in Schuster by making the combination C. rumphii forma undulata. He was, however, still misapplying the concept of C. undulata, which is a synonym of C. circinalis. Stone (1970) returned to use of Schuster's combination, with no mention of Kanehira.

Distinguishing features: Distinguished by the broad, hard, glossy leaflets with some but interrupted laminar hypodermis and adaxial mesophyll interrupted at the broad, low midrib, the relatively long, usually spine-free petiole, and the broad megasporophyll lamina with few (16-20) lateral spines and a short apical spine (10-15 mm long). A broad zone to the south of Guam has no cycads, until the New Britain region is reached. No evidence of intergradation with the more southern species (C. rumphii, C. apoa, C. bougainvilleana) is known. Taxonomy is complicated further to the west, with several recognisable and different taxa that require further study occurring in the region of Yap, Palau and the Philippines.

Distribution and habitat: Micronesia, the Marianas Group and the western Caroline Islands. This species does not extend west into the Philippines, but is replaced by related species in comparable habitats (Amoroso 1986). This species occurs in closed forest country on coral limestone or coral sand, or occasionally on volcanic soils on islands where these occur.

Conservation status:


Stems arborescent, to 8-12 m tall, 14-25 cm diam. at narrowest point.

Leaves deep green, highly glossy, 160 cm long, flat (not keeled) in section (opposing leaflets inserted at 180° on rachis), with 130-140 leaflets, with white and orange tomentum shedding as leaf expands; rachis usually terminated by a spine 4 mm long. Petiole 35-40 cm long (20-25% of total leaf), petiole glabrous, unarmed. Basal leaflets not gradually reducing to spines.

Median leaflets simple, strongly discolorous, 260 mm long, 16.5 mm wide, inserted at 80° to rachis, decurrent for 9 mm, narrowed to 5.5 mm at base (to 30-35% of maximum width), 18.5 mm apart on rachis; median leaflets section flat; margins slightly recurved; apex acute, not spinescent; midrib flat above, raised below.

Cataphylls linear, pungent, pilose, persistent.

Pollen cones fusiform, orange, 40 cm long, 8 cm diam.; microsporophyll lamina firm, dorsiventrally thickened, 40 mm long, 22 mm wide, fertile zone 30 mm long, sterile apex 10 mm long, level, apical spine rudimentary, sharply upturned.

Megasporophylls 30 cm long, yellow-tomentose; ovules 2-6, glabrous; lamina ovate, 45-50 mm long, 38-40 mm wide, shallowly pectinate, with 18-20 pungent lateral spines 2-6 mm long, apical spine distinct from lateral spines, 12-15 mm long.

Seeds flattened-ovoid, 60 mm long, 50 mm wide; sarcotesta orange-brown, not pruinose, 6 mm thick; fibrous layer absent; sclerotesta apically crested. Spongy endocarp present.

The Cycad Pages

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