Rhaphidophora hayi P.C.Boyce & Bogner

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Diagnostic

While resembling Rhaphidophora pachyphylla, R. hayi is immediately distinguishable by the flowering shoots with broader, truncate-based leaf laminas, the raised, larger, elongated, longitudinally orientated stigmatic region, the occasional foraging shoot, and by the presence of free, disarticulating side shoots functioning as vegetative propagation units. This last character occurs also in R. cryptantha (q.v.). Very similar to R. parvifolia Alderw. (Maluku: Pulau Ternate) but differing by the stipitate spadix. From available material it is not possible to tell if R. parvifolia has the disarticulating side shoots typical of R. hayi.

Habitat

Primary and secondary monsoon or rain forest on coralline limestone and basalt.

Distribution

Indonesian Papua, Papua New Guinea (including New Britain, New Ireland, Bougainville and Muyua (Woodlark) Island), and Australia (eastern tropical Queensland).

General Description

Moderate-sized, slender to somewhat robust, semi-leptocaul, homeophyllous neotenic liane to 5 m; seedling stage a non-skototropic shingling juvenile shoot; pre-adult plants forming small terrestrial colonies; LEAVES: adult shoot architecture comprised of clinging, physiognomically unbranched, mostly densely leafy, sterile stems and abbreviated, free, flowering stems; stems rectangular to terete in cross-section, widest side prominently convex, smooth, dark green, without prophyll and cataphyll fibre but with very thin, adherent, petiolar sheath tissue, internodes to 8 x 1 cm, separated by slight ± straight scars, older stems sub-woody; flagellate foraging stems weakly developed, usually at least partially leafy and mostly replaced by short, readily disarticulating free side shoots functioning as vegetative propagation units; clasping roots arising from the internodes, prominently pubescent; feeding roots c. 3 mm diam., brown, minutely pubescent, sparsely lenticellate; leaves distichous, shingling and ascending on adherent shoots, densely arranged or slightly scattered on free shoots, scattered leaves with internodes between carrying a prominent cataphyll of short duration; cataphylls and prophylls membranous, caducous; petiole deeply grooved, 1-2 x 0.2-0.3 cm, smooth, apical and basal genicula barely visible; petiolar sheath prominent, caducous but adhering to stem, membranous, ligulate, margins of ligule fused, the ligule extending up to 3 cm above base of lamina and enclosing shoot apex; lamina broadly to narrowly ovate-elliptic, coriaceous, base truncate to cuneate or cordate (the last not on flowering shoots), and briefly decurrent, apex acute with a tiny tubule; midrib prominently raised abaxially, slightly raised adaxially; primary venation densely pinnate, slightly raised abaxially, somewhat impressed adaxially; interprimaries sub-parallel to primaries, slightly raised on both leaf surfaces; secondary venation reticulate, slightly raised abaxially, ± flush adaxially; INFLORESCENCE solitary, subtended by a membranous, caducous prophyll and one or more similar cataphylls; peduncle slightly laterally compressed, 2-3 x 0.6-1 cm; spathe canoe-shaped, stoutly beaked, 5.5-8 x 2-4 cm, stiffly fleshy, yellow, gaping wide at female anthesis and then slowly falling leaving a large scar at the base of the spadix; spadix stoutly cigar-shaped, shortly stipitate, inserted ± level on stipe, 3.5-6 x 1-1.2 cm, yellow; stipe 4-6 x 3-3.5 mm; stylar region weakly developed, mostly irregularly rhombohexagonal, 1.1-1.3 x 1-1.1 mm, truncate; stigma prominently raised, elongated, longitudinally orientated, c. 0.3-0.5 x 0.2-0.4 mm; anthers not exserted at male anthesis; INFRUCTESCENCE not seen.