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The Cycad Pages
Cycas apoa

Cycas apoa K.D. Hill, "Austral. Syst. Bot. 7: 553-55, fig. 9." (1994). H—CANB
"TYPE: Indonesia, Irian Jaya, Babrongko, S. coast of Lake Sentani, G. Iwanggin BW 5245, 4 Apr 1957 (holo CANB; iso A, BRI, LAE, L)."


Etymology: A rendering of the local vernacular name for this taxon in the Kaka language, as spoken around the Sepik estuary in north-western New Guinea. It is pronounced AP-wah, with the first syllable stressed but short, as in `cap'.

Illustration: Hill 1994c, fig. 9.

Historical notes: Recognised first as a distinct species in 1994.

Distinguishing features: C. apoa is distinguished by the thin leaflets with narrow bases and no laminar hypodermis, continuous adaxial and abaxial hypodermis and strongly undulate margins, and the small megasporophyll lamina with reduced lateral spines. C. scratchleyana from the southern side of the island shares the thin, undulate leaflets, but has a much larger and relatively broader megasporophyll apex with numerous clearly defined lateral spines. The two also share continuous adaxial mesophyll and sometimes continuous abaxial mesophyll. The midrib is also narrow and usually sharply raised in both taxa. This is the species sometimes referred to as C. circinalis in northern coastal new Guinea (Borrell 1989).

Distribution and habitat: Known from northern coastal New Guinea, from the Huon Peninsula west to at least the Mamberamo River in Indonesian New Guinea. This species occupies part of the same geographic range as C. rumphii, and detailed field study would be required to determine the controls on distribution. C. rumphii is, however, a primarily littoral species, whereas C. apoa apparently occurs away from the littoral zone.

Sporadic and scattered, in more or less closed mesophyll forest in wet lowland areas, sometimes in seasonally inundated sites but more often on low ridges.

Conservation status: not considered to be at risk. IUCN (1994) Red List status LR nt.

Vernacular: bico (Ekor village, Halmahera), handambo (Sentani language), apoa (Kaka language, Kasmin village).

Description:

Stems arborescent, to 2.5 m tall.

Leaves bright green, highly glossy, 180-250 cm long, flat (not keeled) in section (opposing leaflets inserted at 180° on rachis), tomentum shedding as leaf expands; terminated by a spine or paired leaflets; 4 mm long. Petiole 35-60 cm long, glabrous, spinescent for 80-100% of length. Basal leaflets not gradually reducing to spines, 140 mm long.

Median leaflets simple, strongly discolorous, 220-300 mm long, 11-14 mm wide, decurrent for 7 mm, narrowed to 2.5 mm at base (to 20% of maximum width), 13 mm apart on rachis; median leaflets section flat; margins undulate; apex softly acuminate, not spinescent; midrib raised above, raised below.

Cataphylls linear, soft, pilose, persistent.

Pollen cones narrowly ovoid, orange; microsporophyll lamina firm, not dorsiventrally thickened, apical spine prominent, sharply upturned.

Megasporophyll lamina lanceolate, 35 mm long, 16 mm wide, obscurely dentate, apical spine distinct from lateral spines; ovules glabrous.

Seeds flattened-ovoid, 45-50 mm long, 40 mm wide; sarcotesta orange-brown; fibrous layer present; sclerotesta smooth. Spongy endocarp absent.


The Cycad Pages

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Written and maintained by Ken Hill 1998-2010
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