Protologue: Taxon 26 (1977): 338
Amorphophallus campanulatus Decne; Amorphophallus campanulatus var blumei Prain; Amorphophallus campanulatus f. Darnleyensis F.M. Bailey; Amorphophallus decurrens (Blanco) Kunth; Amorphophallus malaccensis Ridl.; Amorphophallus paeoniifolius var. campanulatus (Decne.) Sivad.; Amorphophallus rex Prain; Amorphophallus rex Prain ex Hook. f.; Amorphophallus sativus Blume; Amorphophallus virosus N.E. Br.; Arum campanulatum Roxb. [illegitimate]; Arum decurrens Blanco; Conophallus giganteus Schott ex Miq. [illegitimate]: Conophallus sativus (Blume) Schott; Plesmonium nobile Schott.
Tuber depressed globose, to c. 30 cm in diam., c. 20 cm high, weighing to c. 15 kg., dark brown, rootscars prominent, annulate, offsets produced every season, these thick rhizomatous, to c. 10 cm long, to c. 4 cm in diam. Leaf solitary or paired, rarely more. Petiole to c. 2 m long and c. 20 cm in diam., background colour pale to dark green or blackish green, usually with large and small pale blotches and numerous tiny dark dots, the large blotches often confluent, especially near the base, surface shallowly corrugate to strongly echinate-verrucate. Lamina highly dissected, to c. 3 m in diam., rachises narrowly or broadly winged almost to the base. Leaflets rounded, oval, ovate, obovate, elliptic, elongate elliptic, elliptic-oblong, acuminate, 3-35 cm long, 2-12 cm in diam., upper surface mid green, lower surface mid green or pale green. Inflorescence short peduncled. Peduncle 3-20 cm long, 1-8 cm in diam., usually paler and smoother than petiole. Spathe campanulate, broader than long, 10-45 cm long, 15-60 cm in diam., base and limb often separated by a shallow constriction. Limb spreading, strongly undulate, base outside vary variable, background colour ranging from pale green to dark brown, usually with large and small, circular paler spots, base inside lower part deep maroon, upper zone dirty whitish or very pale pinkish, limb outside as base but with more prominent maroon flushes, especially near the margin, limb inside usually glossy dark maroon, base within densely verrucate, verrucae variable, mostly conical, fleshy. Spadix sessile, shorter or longer than spathe, 7-70 cm long. Female zone cylindric, 3-25 cm long, 1-12 cm in diam; flowers congested or slighlty distant. Male zone cylindric or strongly obconic, 2.5-15 cm long, 1-10 cm in diam. at the base, 1-20 cm in diam. at the top; flowers congested. Appendix very variable, inflated, 1.5 30 cm long, 1.2-30 cm in diam. (slightly above the base), globose, depressed globose, oval or triangular conic (pyramidal), smooth or with various folds and/or irregular shallow depressions, base often with flattened, staminodial structures, top obtuse or acutish, surface minutely granulate, glossy dark maroon, rarely pinkish or yellow, giving off a stench of rotting meat. Ovaries depressed, circular in cross-section, 3-5 mm in diam., 1.5-2.5 mm high, entirely pale green or largely maroon with a whitish base. Style slender, 3-15 mm long, maroon. Stigma large, oval or triangular in cross-section, 4-7 mm in diam., 3-5 mm high, often strongly laterally compressed, then cordate in longitudinal section, shallowly or deeply 2- or 3-lobed, lobes rounded or conic, sometimes with a strong groove on the outward facing side, surface verruculate, pale or deep yellow. Male flowers consisting of 4-6 stamens. Stamens 4-6 mm long. Filaments c. 0.5 mm long. connate. Anthers cylindric, 3.5-5.5 mm long, c. 1.5 mm in diam., subtruncate, off white. Infructescence long peduncled. Peduncle stretching strongly after fertilisation, 20-100 cm, colour changing to uniformly tan, surface with myriads, narrow, transversal cracks. Berries closely set or slightly distant, elongate, ripening from green, via yellow to bright red, 1.5-2 cm long, 8-10 mm in diam.
Madagascar, eastward via India to Malesia, Thailand, Indochina, southern China, Polynesia and northern Australia (Hetterscheid & Ittenbach 1996)
Secondary forest, forest edges, teak-forest, village groves, thickets, highly disturbed areas, in part shade or fully exposed areas; up to 800 m altitude (Backer & Bakhuizen van den Brink 1968; Hetterscheid & Ittenbach 1996).
Notes: Amorphophallus paeoniifolius is easily recognised by its sessile, broadly campanulate spathe and often huge, heavily wrinkled, conical appendix. See also notes under Amorphophallus hirsutus.
The species has a long history of cultivation and has probably escaped and became weedy in many areas in its present-day distribution. It is therefore suggested that most parts of its geographical range is unnatural and the result of escaping cultivation. It is therefore impossible to pinpoint its “natural” geographical distribution. Strict morphological separation of cultivated and weedy material is impossible despite many attempts by different authors. Any ICBN based name of such weedy material is rejected here. It is advisable to identify cultivars and name them accordingly but not as proper taxa.
Amorphophallus paeoniifolius is a common species in Java. There are two common names for the species namely ‘walur’ and ‘suweg’, based on petiole surfaces. The former has very rough petioles, grows wild (weedy) and the tubers are not edible, whereas the latter has an almost smooth petiole, is cultivated and the tubers are eaten. Mostly, ‘suweg’; is cultivated for its edible tubers, notably in Central and East Java. Javanese people usually have a special treatment to remove the oxalate crystals from the tuber, by leaving the slicing tuber outside under the sun and rain for several days before cooking. For some people, another treatment used to remove oxalate crystals is by placing the tuber under running water, followed by soaking in saline water for several hours before using it.