Stem broadly fistular, finely striate, glabrous, probably juicy, ± 5 mm. wide at the base, with rather few, opposite (occasionally verticillate) or alternate, long, slender and ascending branches above.
Basal leaves apparently few (2–3), 30–42 × 10–28 cm., the lamina oblong-ovate to flabellate, 1–2-pinnate with 2–4 pairs of sessile or petiolulate pinnae, leaflets and pinnae broadly decurrent along the axes and petiole in large forms; leaflets narrowly to broadly oblong, ± obtuse, ± 6.5–12 × 1–5 cm., with broad but sharply mucronate, divergent teeth, glabrous or more usually sparingly to densely furnished with coarse, long, stramineous, setose hairs on the lower surface of the primary venation; petioles setose or glabrous, 12–20 cm. including the 6–7 cm., broad, striate sheaths; stem leaves with distinct lamina 1–2 only, reduced; bract-like leaves numerous in the flowering part of the stem.
Erect perennial (? or biennial) herb, ± 0.8–0.9 m., with a broadly ellipsoid tuber 3–4 cm. long.
Fruit oblong or oblong-obovate, glabrous, slightly emarginate at base and apex, 9–13 × 5–7 mm., the fertile centre 2.5–3 mm. wide; commissural vittae 4–6, very obscure and ± concealed by overlying tissue; vallecular vittae solitary; stylopodia conical but very low, edge of narrow disk ± crenulate; styles short, deflexed or divergent, shorter than the stylopodia.
Petals oblong or elliptic, ± 1 mm., creamy- or greenish-yellow sometimes suffused with purple dorsally, glabrous, univittate.