Homalomena rostrata Griff.

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

Distribution

Malesia: S Peninsular Thailand (Narathiwat), Sumatera, Peninsular Malaysia, Borneo, Maluku (Pulau Ceram).

Diagnostic

Helophytic. Leaves sub-linear to broadly ovato-oblong; spathe conspicuously constricted; spadix up to 14 cm long, male and female flower zones contiguous, interpistillar staminodes present.

Habitat

Swampy areas in lowland forest, forest margins, in freshwater or peatswamp, or wet facies of kerangas, or kerapah, often, but not exclusively, in full sun.

General Description

Clump or colony-forming stoloniferous very strongly aromatic (terpenoids – ocimene or carene?) usually helophytic herbs to c. 1 m tall. Stem an erect to creeping rhizome to c. 20 cm long, c. 2 cm thick, somewhat spongy, emitting cataphylliferous stolons to c. 25 cm long, 1 cm thick, these eventually upturned, becoming rhizomatous, leafy, and thence emitting further stolons from the base of the rhizomatous portion. Leaves clustered, up to c. 20 together; petiole 10–50 cm long, distally weakly to rather strongly D-shaped in cross-section , rather spongy within, deep-green to dark red or brown, especially for the basal half, with conspicuous broken dark green to brown longitudinal striations, sheathing in the lower 1/3 to half; petiolar sheath broadly winged, the wings spreading and somewhat fleshy, sheath open, the petiole essentially canaliculate in cross-section; lamina deep green to deep brown, glossy, very variable in overall shape, ranging from sub-linear to broadly ovato-oblong, leathery, c. 10–50 cm long, 3–25 cm wide, the apex ranging from acuminate to broadly obtuse, abruptly and shortly acuminate for c. 1 cm, finally stiffly apiculate for c. 10 mm, base decurrent-cuneate to truncate, shallowly cordate to sagittate or hastate, usually distinctly asymmetric, posterior lobes where present straight to rather widely divergent, up to 12 cm long, truncate, rather regular in size, 1–2 mm across, polygonal, slightly sinuous on the abaxial side, the thecae overtopped by a pronounced synconnective. Infructescences declinate by flexing of the peduncle; spathe persistent, turning deep red; at fruit maturity spathe shed by the abscising of the lower spathe at the insertion on the peduncle. Fruit oblong-globose, dull red, smelling strongly of butyric acid. Seeds elongate-ellipsoid, c. 1 × 0.3 mm, very finely longitudinally striate, pale brown. somewhat acutely rounded; midrib adaxially flat, abaxially prominent, with c. 5–7 adaxially impressed abaxially rather prominent primary lateral veins on each side, posterior lobes where present with 2 or 3 clustered veins running into them, primary lateral veins alternating with somewhat fainter interprimaries and diverging all at c. 60º from the mid-rib. Inflorescences 2–3 together, the synflorescence subtended by a conspicuous prophyll; peduncle 8–15 cm long, 5–10 mm diam., robust and somewhat spongy, medium green to reddish or brown, especially near the base, exceptionally glossy bright red. Spathe externally green, flushed red, or more rarely deep red, rather glossy, internally somewhat pale, rather variable in size, 5–15cm long, conspicuously constricted at a point corresponding to the top of the female flower zone; opening by inflation of the lower spathe and loosening of the spathe limb (female anthesis), and then spreading of the spathe limb (male anthesis); post anthesis spathe closing and tightly clasping the spadix; lower spathe oblongo-ovate to ovato-globose, c. 1/3 spathe length, up to 5 cm long, 2 cm wide, externally with conspicuous glands (extrafloral nectaries?); spathe limb narrowly to somewhat broadly triangular, c. 2/3 spathe length, up to 7 cm long, 3 cm wide, rostrate-apiculate for c. 10 mm. Spadix subequalling the spathe, up to 14 cm long; shortly stipitate; stipe c. 6 mm; female flower zone weakly to rather strongly fusiform, up to 5 × 1.5 cm; pistils subglobose, 1–2 mm diam., green to red depending on the overall colour of the spathe, red pistils associated mainly with red or red-flushed spathes; stigmas subsessile, discoid to rather well-lobed, slightly wider than the ovary, occasionally remarkably robust, papillate at anthesis; interpistillar staminodes weakly to very strongly clavate, subequalling the associated pistil, waxy white; male flower zone tapering-cylindrical, up to 10 cm long, 1 cm wide, tapering to an acute tip, ivory to very pale yellow; male flowers irregular 3–4-staminate; stamens