Apoballis rupestris (Zoll. & Moritzi ex Zoll.) S.Y.Wong & P.C.Boyce

Moderately to very robust herb to c. 1 m high. Stem erect to decumbent, up to 2 m long (usually less), c. 3–10 cm diam. with internodes c. 1–5 cm long. Leaves several together; petiole green to brownish red, c. 18–90 cm long, sheathing in the lower ⅓–½; wings of sheath fully attached, tapering, marcescent and crumbling; blade ovato-sagittate, sometimes slightly cordate-sagittate, green to mid-green adaxially, dull yellowish green abaxially, thinly leathery, c. 23–40 cm long × c. 16-28 cm wide, the base divided with posterior lobes acute to rounded, c. 5-12 cm long, the apex acuminate; midrib abaxially prominent, with c. 15–24 primary lateral veins on each side, sometimes branching, prominent abaxially, sunken adaxially, diverging from the midrib at 50°–70°, alternating with lesser interprimary veins; secondary and tertiary veins obscure; posterior costae absent. Inflorescences 4–6 together, subtended by dried cataphylls; peduncle yellowish green, sometimes tinged red at the base, c. 10 cm long. Spathe c. 17 cm long, slightly curved, constricted at the level of sterile zone of the spadix; lower spathe c. 6 cm long, c. 2.2 cm diam., narrowly ovoid, yellowish green; the limb narrowly lanceolate, pale yellow, c. 11 cm long, c. 1 cm diam., open only slightly between male zone and lower part of appendix during anthesis, withering. Spadix subequalling the spathe, sessile; female zone light green, c. 4.5 cm long, c. 1.2 cm diam. at the base, not or barely adnate to the spathe; ovary subcylindric, c. 2–2.5 mm long, c. 0.75 mm diam.; stigma raised on a very short style, rounded (button-like); interpistillar staminodes scattered among the pistils, dirty white, taller than the pistils, a few concentrated at the base and more crowded between female zone and sterile inyterstice; sterile interstice almost naked, c. 1–2 cm long, the base of staminodes sometimes somewhat sunken into spadix, crowded at the base then scattered toward the apex; male zone yellowish-ivory, c. 3.5 cm long, c. 0.8 cm diam., cylindric; anthers c. 0.5 mm across, dumbbell-shaped; appendix subequalling or longer than male zone, c. 5 cm long, tapering, creamy, c. 0.5–0.8 cm diam. at the base; staminodes of appendix irregularly hexagonal. Fruiting spathe urceolate, to 5 cm long.