Homalomena borneensis (Araceae)
Medium, rather robust strongly aromatic (mango-resin) evergreen glabrous herbs to ca 85cm tall. Stem pleionanthic, erect, up to ca 3 cm thick, pale green, internodes to ca 1.5 cm long. Leaves up to ca 15 together, ca 5 per module; petiole weakly D-shaped in cross section, erect, 15 – 45 cm long, obscurely pulvinate ca ⅔ along length, pulvinus ca 2 cm long; petiole bases clasping, pale green, sometimes suffused reddish for the basal ¼, matte, drying medium brown, petiolar sheath ca 9 – 20 cm long, ca ⅓ of petiole length, equal, decurrent at apex, margin erect when fresh, margins membranous, pale green, persistent, occasionally slightly scarious on the oldest leaves, these oldest sheathes often red; lamina ovate to very weakly ovato-sagittate, 10 – 22 cm long × 9 – 15 cm wide, thinly leathery, pale green adaxially, drying medium olive-brown, abaxially slightly glaucous (fresh), drying glaucous pale brown, base subtruncate to very shallowly cordate, posterior lobes absent or very short, straight, if present then ovato-triangular, 0.5 – 3 cm long, tip acute, acuminate for ca 1 cm thence tubular-apiculate for ca 2 – 3 mm; midrib raised abaxially (fresh and dry), glaucous green when fresh, adaxially sunken slightly into lamina, ca 3 mm wide, with ca. 7 – 10 primary lateral veins on each side, diverging at 30° – 70° from the midrib, adaxially impressed (fresh), flush with lamina when dry, abaxially slightly raised (fresh and dry), distal-most veins curved slightly towards the apex when near the margin, interprimary veins ca ¼ width of the primary lateral veins, alternating with primaries; secondary venation very obscure, striate; tertiary venation not visible, all veins running into a slightly thickened intermarginal vein. Inflorescences up to 6 together, erect and smelling powerfully of anise during female anthesis, thence by flexing of the peduncle sinuous-declinate, each subtended by prophyll, to ca 10 cm long; peduncle to ca 15 cm long × ca 3.5 mm diam., pale green. Spathe 9 – 11 cm long, tightly furled prior to anthesis, lower spathe inflating and spathe limb loosening at female anthesis, thence inflating and then opening wide, entire spathe white at anthesis; lower spathe ovoid-ellipsoid, equalling spathe limb, 5 – 6 cm long, constricted at the junction of the spathe limb, the constriction coinciding with junction of the male and female flower zones; spathe limb ovato-triangular, ca 5 – 6 cm long × ca. 3.5 cm wide (at male anthesis), spathe limb margins recurving at male anthesis, apex mucronate to ca 5 mm long. Spadix subequalling the spathe, ca 9 – 10.5 cm long, stipitate; stipe ca 4 mm long × 3 mm diam., cylindrical, inserted obliquely on peduncle, white; female flower zone ca 4.5 cm long × ca 1 cm wide, ca ½ length of spadix, stoutly fusiform; pistils ca 1.3 mm × 0.75 mm, densely arranged, globose-cylindrical, white; stigma globose-capitate, slightly exceeding the ovary and coherent with its neighbours, staining deep brown in alcohol, each pistil associated with one interpistillar staminode; interpistillar staminodes clavate on a stout stipe ca 0.4 mm diameter, equalling or slightly overtopping the associated female flower, waxy white; suprapistillar interstice zone ± absent; male flower zone more-or-less contiguous with female flower zone but markedly narrower, to ca 5 cm long, ca ½ length of spadix, separated from female zone by the prominently truncate upper part of the latter, with the lowest portion of male flower zone comprised of sterile male flowers intergrading into a single row of staminodes intermixed, this zone separated from the remainder of the male flower zone by a distinct constriction; male flowers ca 3 mm × 2 mm trapezoid, comprising 3 – 5 truncate stamens, each overtopped by a large, flat connective. Infructescence declinate, spathe entirely persistent, pale green, somewhat glaucous, ripening mid-green, less often deep red, peduncle matte medium green. Fruits & seeds not observed.
Not Evaluated (IUCN Category: NE)
The leaf laminae almost always lacking posterior lobes, and pale green, rather matte adaxially and moderately to conspicuously glaucous abaxially are diagnostic throughout Sarawak. The spathe limb shorter than the lower part of the spathe is shared by H. borneensis, H. clandestina, along with numerous undescribed species. Homalomena borneensis may be distinguished by the male flower zone being contiguous with the female flower zone (not separated by a naked interstice); the female flower zone being stoutly fusiform, with densely arranged pistils that are not ascending, and with coherent stigmas. Sterile plants are immediately recognizable by the leaf lamina abaxially glaucous with rather few primary lateral veins. Homalomena ovata Engl. non. (Schott) Hook.f., a nom. illeg. based on a specimen from Matang, Kuching, is incontrovertibly the same as H. borneensis.
Borneo: Sarawak, widespread west of the Rejang valley. This species is also recorded, but yet to be confirmed, from scattered localities in Kalimantan Barat, Kalimantan Tengah & west Kalimantan Timur.
Evermoist to slightly seasonal evergreen forest on sandstone or shale-derived clays with a deep leaf litter layer.
The Iban community of the Batang Ai drainage (Sarawak: Sri Aman Division) utilize H. borneensis as an antidote to snakebites, scorpion stings, etc. The bitten area is kept in the smoke of the burning stems (reported as rhizomes) as long as the patient can stand it. The leaves are used in post-partem petangas, a herbal sauna. The rhizomes are also used to treat sick chickens by keeping them in the smoke from burning ‘rhizomes’ of this and other species. Traditionally burning rhizomes were also used to keep monkeys away from fields. The aromatic rhizome is used in perfume mixtures. The ripe fruit is edible, with a sourish taste.