Evergreen herb with a rhizome up to 3/4 cm thick, which is slenderer in submerged specimens with long internodes. Runners are (5) 10–15 cm long and slender. Leaves have petioles reaching up to 15 cm; the blade is more or less smooth, ovate to narrowly ovate, measuring (1) 1.5–3.5 (4) x (3) 5–10 (15) cm. The upper leaf surface ranges from dark green to brown or reddish, while the lower surface is paler green to reddish, usually with prominent reddish veins; the apex is acute to acuminate, the base is obtuse to cordate, and the margin is entire to subundulate. The spathe is 4–12 cm long and brownish on the outside. The spathe kettle is 0.8–1.5 cm long, with a reddish-purple interior in the upper part and alveoli covering nearly the entire surface. The spathe tube is 1.5–6 cm long and usually features a distinct red-purple "collar" zone at the top. The spathe limb is 1–3 cm long, suberect, twisted to recurved, and smoothish; its color is greenish to yellowish or brownish, sometimes reddish, with a dark purple to reddish collar. The spadix is 1.0–1.5 cm long, bearing 4–8 pistils with rounded to ovate stigmas and 20–40 male flowers.