Apoballis okadae (M.Hotta) S.Y.Wong & P.C.Boyce

Small to moderately robust rheophytic herb c. 15–40 cm tall. Stem creeping to decumbent, with internodes to 1–4 cm long, 1–3 cm thick. Leaves several along the stem; petiole generally longer than the blade, 5–40 cm long, sheathing in the lower 2⁄5–3⁄5; wings of sheath fully attached (later tending to degrade) and tapering; blade oblanceolate to ovate, 7–26 cm long × 2–10 cm wide, the base acute to shallowly cordate, sometimes markedly asymmetric, the tip acuminate for 1–3 cm; midrib and primary veins tough and abaxially prominent; primary lateral veins 3–9 on each side of the midrib, irregularly alternating with interprimaries ill-differentiated from the secondary venation, diverging at c. 30°; secondary venation mostly arising from the midrib, some from near the bases of the primary veins in the lower part of the leaf; tertiary venation obscure. Inflorescence solitary; peduncle more or less half the length of the petiole at anthesis (later elongating). Spathe green, 5–8 cm long; lower spathe narrowly ovoid to ovoid, 2–3 cm long, differentiated from the limb by a weak constriction; limb oblong-lanceolate, shortly acuminate, 3–5.5 cm long, whitish, persistent after anthesis, finally deciduous. Spadix shortly stipitate, 3–3.5 cm long; female zone and stipe obliquely inserted to partly adnate to the spathe in the basal ¼; female zone 1–1.5 cm long, subcylindric, c. 2 mm diam. (dry); pistils crowded (distally more lax), oblong-subglobose, c. 0.5 mm diam.; stigma sessile, discoid, slightly narrower than the ovary; interpistillar staminodes absent from among the pistils, a few or an incomplete whorl at the base of the female zone, more or less globose, sessile, slightly larger than the pistils; sterile interstice 5–8 mm long, within and reaching the mouth of the lower spathe chamber, naked except for scattered small groups of sessile staminodes smaller than the basal ones, c. 0.3 mm diam.; male zone more or less cylindric-fusiform, c. 1.2–2 cm long × 3–5 mm thick; stamens crowded, truncate with the connective thick but not elevated between the thecae, c. 0.6 mm across; appendix shorter than and basally isodiametric with the male zone, c. 5 mm long, apically acute; staminodes of the appendix flat-topped, irregularly polygonal, c. 0.7 mm diam. Fruiting spathe urceolate becoming pyriform, c. 3–4 cm long.