Amorphophallus paeoniifolius (elephant yam)
A striking aroid from tropical Asia, elephant yam is extensively cultivated for its edible tubers.
About this species
Elephant yam is a striking aroid with a flower spike crowned with a bulbous maroon knob and encircled by a fleshy maroon and green-blotched bract. The solitary leaf, which emerges after the flowering parts, resembles a small tree.
Amorphophallus paeoniifolius has been in cultivation throughout tropical Asia for centuries. The tubers are the third most important carbohydrate source after rice and maize in Indonesia. They are also consumed widely in India and Sri Lanka, although elsewhere they are seen as a famine crop, to be used when more popular staples, such as rice, are in short supply.
Elephant yam belongs to the same genus as the crowd-pulling titan arum (Amorphophallus titanum). It should not be confused with Dioscorea species, which are also known by the common name yam, but belong to a different plant family (Dioscoreaceae). In particular it should not be confused with elephant’s foot yam (Dioscorea elephantipes) from South Africa.
Geography & Distribution
Amorphophallus paeoniifolius in cultivation (Image: licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license)
Amorphophallus paeoniifolius is considered to be native to southern China (including Taiwan), Bangladesh, India, Sri Lanka, Laos, Burma, Thailand, Vietnam, Borneo, Java, Malaya, Philippines, Sulawesi, Sumatra, New Guinea, northern Australia, Fiji and Samoa.
It is found in secondary forest or highly disturbed areas, up to 800 m above sea level.
It is considered naturalised in Madagascar and the Seychelles.
Elephant yam has been in cultivation throughout tropical Asia for centuries. It has been widely transported by humans and easily escapes from cultivation to become naturalised, so that its natural distribution is not clear.
Specimen of Amorphophallus paeoniifolius from Kew's Herbarium
Overview: Perennial herb. A single inflorescence (flowering structure) is produced, followed by a solitary leaf. After the growing season, this dies back to an underground storage organ (tuber).
Tuber (thickened part of underground stem): Dark brown, flattened-globe-shaped, up to 50 × 30 cm with prominent root scars. Weighing up to about 15 kg.
Leaves: Usually one (sometimes two) per tuber. Petiole (leaf stalk) up to 2 m tall and 20 cm in diameter with rough, warty surface. Background colour pale to dark green or blackish-green with pale blotches and numerous tiny dark dots. Leaf blade up to 3 m in diameter and deeply divided into segments. Leaflets up to 35 × 12 cm.
Spadix (flower spike): Up to 70 cm long. The lowermost portion of the spadix is female and is covered with pistils (female parts). Each pistil consists of a pale green or maroon ovary with a maroon stalk (style) and two- or three-lobed yellow head (stigma). The next floral zone is male and contains tightly-packed yellowish stamens. At the tip of the spadix is a bulbous, dark maroon, rounded to deeply wrinkled appendix.
Spathe (bract surrounding spadix): Bell-shaped, broader than long, up to 45 × 60 cm, pale green to dark brown with paler blotches on exterior. Opening outwards to form a frilled, glossy maroon, collar-like structure around the spadix. Basal portion of interior pale green-yellow.
Fruits: About 2 × 1 cm, bright red when ripe. Borne on a spike up to 50 cm long and 8 cm in diameter, the fruiting part held aloft on a peduncle (stalk) 20–100 cm long.
The flower spike (spadix) emits an odour reminiscent of rotting flesh, which attracts pollinators such as carrion flies and beetles.
Edible tubers from elephant yam (Image: Aravind Sivaraj, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license)
Elephant yam is widely cultivated for its edible tubers, which are an important source of carbohydrate in India and Indonesia and a valued secondary crop throughout tropical Asia. It can be found on sale further afield (including Hounslow, not far from Kew in the UK) in international food markets.
It is also widely used as fodder.
Elephant yam has medicinal properties and is used in many Ayurvedic (traditional Hindu) preparations. The tubers are considered to have pain-killing, anti-inflammatory, anti-flatulence, digestive, aphrodisiac, rejuvenating and tonic properties.
They are traditionally used in the treatment of a wide range of conditions including parasitic worms, inflammation, coughs, flatulence, constipation, anaemia, haemorrhoids and fatigue.
Further research is needed to determine the pharmacological properties of elephant yam.
Elephant yam is cultivated as an ornamental for its striking compound foliage and unusual and dramatic flowering and fruiting structures.
This species at Kew
Elephant yam can be seen growing in the Tropical Carnivorous Zone (Zone 8) of the Princess of Wales Conservatory at Kew.
This newly redeveloped zone is home to many other species including Nepenthes truncata, N. rafflesiana, N. vietchii, N. bicalcarata and the recently described N. robcantleyi. The zone also features voodoo lily (Amorphophallus variabilis) and a new hybrid at Kew A. decus-silvae × gigas, plus a range of epiphytic ferns and orchids including Bulbophyllum species.
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