Araceae
Aridarum borneense (M.Hotta) Bogner & A.Hay
SUMMARY
Rheophytic herb 30–60 cm tall. Stem condensed, c. 4–10 cm long, c. 2–3 cm diam. Leaves c. 5 together, distichous, held in a more or less horizontal fan; petiole (4–)6–40 cm long, 0.2–1 cm diam., sheathing at the extreme base, the wings extended into a very narrowly triangular ligular portion 6–20 cm long which dries reddish brown; blade narrowly elliptic to oblong elliptic, 9–32 cm long × 2.5–11 cm wide, coriaceous, mid- to dark green adaxally, paler abaxially, the base cuneate, the apex acute to broadly acute and apiculate for 0.5–1.4 cm; midrib abaxially prominent, with 4–9 primary lateral veins on each side diverging at c. 45° and running to a marginal vein; secondary venation adaxially obscure, abaxially faint; tertiary venation forming an inconspicuous tessellate reticulum. Inflorescence solitary, usually nodding; peduncle subequalling the petioles. Spathe 6–8.5 cm long, broadly ovate, apiculate for c. 1 cm, not constricted, the lower c. ⅓ green, convolute and persistent, the upper part white, gaping and then caducous. Spadix subcylindric, blunt, 4–6 cm long, 0.8–1 cm diam.; female zone c. 2 cm long, obliquely adnate to the spathe at the base; pistils crowded; ovaries globular to slightly ellipsoid, 1–1.2 mm diam., with basal and apical placentas, the basal placenta bearing numerous orthotropous ovules, the apical placenta naked or with abortive ovules; stigma sessile, discoid, almost as wide as the ovary, centrally impressed, minutely papillate; interpistillar staminodes absent from among the pistils, confined to one or two irregular whorls at the base of the female zone, stipitate, slightly capitate, about as high as the pistils; sterile interstice a few to several whorls of sterile stamens with centrally impressed tops c. 0.4 mm diam.; male zone 3.5–4 cm long, fertile to the apex, pale yellow; stamens crowded, arranged at least in the lower 2/3 of the zone in precise pairs with connate filaments, rectangular from above, 0.8–1 mm across, deeply centrally impressed; thecae on distal and proximal (with respect to spadix axis) sides of the stamen, each with a minute more or less onion-shaped projection (horn) from which the pollen is extruded. Fruiting spathe obconic, c. 2 cm diam.