Homalomena expedita (Araceae)
Colony-forming stoloniferous strongly aromatic (terpenoids – anethol?) helophyticherbs to c. 75 cm tall. Stem an erect to creeping rhizome to c. 30 cm long, c. 4 cm thick, spongy, emitting cataphylliferous stolons to c. 40 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. 10 together; petiole to c. 45 cm long, spongy within, pale mid-green with broken darker green longitudinal striations, sheathing in the lower 1/3; petiolar sheath margins mainly in-rolled except at the base, sheath thus closed; lamina mid-green on both sides, initially glossy, later becoming matt, very broadly ovato-sagittate, leathery, c. 15–20 cm long and wide, the apex broadly obtuse, very abruptly and shortly acuminate for c. 1 cm, finally stiffly apiculate for c. 3 mm, the base shallowly cordate to almost truncate, usually distinctly asymmetric, with widely spreading rounded to subtriangular posterior lobes 7–10 cm long; midrib adaxially flat, abaxially slightly prominent, with c. 5 adaxially impressed abaxially slightly prominent primary lateral veins on each side (plus a cluster of 2 or 3 on each side running to the posterior lobes), alternating with fainter interprimaries and diverging at c. 60º. Inflorescence solitary; peduncle 7–20 cm long, rather thick and spongy, c. 8 mm diam., erect. Spathe green, c. 5 cm long, 1.5 cm across and in bud slightly inflated at level of female zone, thence subcylindric-tapering, but not constricted, later very narrowly ovoid, apiculate for c. 4 mm. Spadix 4.5 cm long, stipitate; stipe c. 6 mm; female flower zone more-or-less cylindric, 0.8–1.2 cm long (irregular length around circumference of spadix), 1.2 cm wide; pistils subglobose, 1–2 mm diam.; stigmas subsessile, discoid or very weakly lobed, slightly narrower than the ovary, papillate; infrapistillar staminodes absent, sterile interstice conspicuous, 1.5 cm long, naked, pale green and c. 6 mm diam. in the lower 1 cm, with more or less regular spirals of low domed warts c. 0.5 mm diam., the upper part (comprising the base of the male zone) 9 mm diam., ivory and clothed in irregular sterile stamens: fertile male zone elongate-bullet-shaped, 1.5 cm long, tapering to a blunt acute tip, ivory; male flowers irregular (1–)2–4-staminate; stamens truncate, irregular in size, 1–1.5 mm across, irregularly polygonal, slightly sinuous on the abaxial side, the thecae overtopped by a synconnective. Fruit unknown.
Leaves very broadly ovato-sagittate; spathe not constricted; spadix about 4.5 cm long, with a conspicuous warty interstice between the male and female flower zones, interpistillar staminodes absent.
Malesia: endemic to Sarawak; there known from the extensive type locality, a tiny relictual population along Jalan Steven Yong (Kuching/Bau border), and also sighted near Sibu along the main road to Miri.
Forming large, probably clonal colonies in open swamps and ditches at low elevation, sometimes in tidal mud with Cryptocoryne ciliata (Roxb.) Fisch. ex Wydler, and mangroves.
Homalomena expedita is quite often seen in cultivation in Sarawak; it seems likely that other populations than those listed above exist and are the source of these cultivated plants. Intriguingly, it is also encountered for sale in markets in Bangkok, with the sellers consistently claiming that the plants originate from southern Thailand. Given the widespread range of other Asian helophytic aroids (e.g., Homalomena rostrata, Cryptocoryne ciliata, Aglaodorum griffithii) it is by no means impossible that H. expedita is much more widespread but simply overlooked; its close resemblance, at least at a distance, to weedy Pontederiaceae might in part explain this.