The character that separates Z. rehmannii from all other species is its lanceolate leaves which are cuneate at the base, not lobed. The colour range of the spathe, from ivory-white, through pink to dark maroon, also seems to be unique. The plants are not as robust as the majority of species; the spathe is more tightly folded into a narrow tube with the limb tapering into a recurved apiculus. The maturing fruits enlarge and their weight bends the withering peduncle until the spathe tip touches the ground where the seeds germinate and sometimes disappear underground.
Deciduous perennial herb, up to 0.8 m high. Leaves narrowly lanceolate, 150-400 x 20-70 mm. Peduncle up to 0.6 m long. Spathe 110-120 mm long, 15-20 mm broad, white-pink-dark maroon.
Plants glabrous from 24-80 cm tall but usually between 40-60 cm. Leaves deciduous, petiolate, up to 40 cm long: petioles 10-20 cm long, clasping at the base: blade dark green, immaculate, lanceolate, acuminate, subulate at the apex, cuneate at the base. 15-40 cm long. 2-7 cm broad. Peduncle up to 60 cm long, green, glabrous, channelled. Spathe 11-12 cm long. 1.5-2 cm broad, folded from the base for two thirds of its length into a narrow funnel, colour ranging from white through shades of pink to dark maroon (almost black), immaculate at base within, limb slightly spreading, recurved, with a tapering tip. Spadix usually stipitate about half as long as the spathe; male zone about 2.2 cm long, anthers yellow, pollen white: female zone about 0.8 cm long. Fruit with 2-4 ovules: up to 6 seeds. The flowering period is, more or less, from September until February with a peak in November.