Rhaphidophora versteegii Engl. & K.Krause

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

Distribution

Indonesian Papua, Papua New Guinea (including New Ireland). Seemingly widespread but, based on known collections, perhaps not common.

General Description

Robust, large, pachycaul, heterophyllous liane to 20 m; seedling stage not observed; pre-adult plants shingling; adult shoot architecture comprised of clinging, physiognomically unbranched, densely leafy flowering stems; stems smooth, mid-green, with cataphylls and prophylls persistent and drying dark yellow, degrading into parchment-like remains, internodes 1-4 x 0.4-2.5 cm, separated by very prominent slightly oblique leaf scars; flagellate foraging stem absent; clasping roots densely arising from the nodes and internodes, smooth and drying with parchment-like epidermis; feeding roots not observed; LEAVES distichous; cataphylls and prophylls chartaceous, degrading into strips of tissue and weak fibres at tips of flowering shoots; petiole deeply canaliculate, 8-48 x 0.4-0.8 cm, smooth, with faint to rather prominent dark dense speckling, apical geniculum prominent, basal geniculum very large but not prominent; petiolar sheath extending to apical geniculum, broad, chartaceous, short-persistent, degrading to papery strips and sparse fibres, then falling; shingling lamina entire, cordiform, 2.5-7.5 x 3-6.5, chartaceous, base cordate, posterior lobes overlapping, apex obtuse and minutely apiculate; adult lamina entire to slightly or extensively perforated, perforations elliptic to rhombic, extending from c. 1/4 to entire width of lamina on each side of the midrib, lamina ovate-elliptic to oblong-lanceolate or oblong-elliptic, slightly oblique, 33-57 x 9.5-27 cm, sub-membranous, drying pale grey-green to bright green, base rounded to acute, apex acute to acuminate; midrib prominently raised abaxially, ± flush adaxially; primary venation pinnate, prominently raised abaxially, weakly so adaxially; interprimaries sub-parallel to primaries, less prominent than interprimaries, slightly raised abaxially and adaxially; secondary venation feebly reticulate to subtesselate; INFLORESCENCE very rarely solitary, usually several together, each subtended by a prominent chartaceous prophyll and one or more chartaceous cataphylls, the entire synflorescence emerging from a mass of dried, chartaceous cataphyll remains; peduncle slender to stout, terete, partially to completely obscured by cataphylls, 4-12 x 0.2-0.8 cm; spathe slender canoe-shaped, hardly to stoutly beaked, 5-10.5 x 1-2 cm, stiff-fleshy, very thick-walled (up to 1 cm at tip), yellow to yellow green, marcescent to early fruiting, eventually falling leaving a prominent scar; spadix stoutly cylindrical, sessile, inserted almost level on peduncle, 3-9.5 x 1-1.5 cm, white at male anthesis; stylar region conical, mostly hexagonal in top view, 0.9-1.2 x 1-1.1 mm; stigma punctiform, very prominently raised, those at the tip of the spadix even more raised, 0.1-0.2 x c. 0.3 mm, glossy, almost black in dried material; anthers exserted at male anthesis; INFRUCTESCENCE stoutly oblong-cylindrical, 6-9 x 1.4-2 cm.

Habitat

Lowland to lower montane primary to secondary rain forest on clays and silts.

Diagnostic

Rhaphidophora versteegii is most similar to R. spathacea in having clusters of inflorescences subtended and interspersed by chartaceous prophylls and cataphylls. It is readily identifiable, and distinguished from R. spathacea, by the distinctive pale grey-green colour of dried material and the form of the juvenile growth phase. Further, leaf lamina perforations occur in most (but not all) individuals of R. versteegii; laminas of R. spathacea are never perforated. The arrangement and shape of the juvenile shingling leaves of R. versteegii are unique in the genus although known from only one collection (Croat 5252).