Konjac (or konjak, English: KON-yak, KON-jak) is a common name of the East and Southeast Asian plant Amorphophallus konjac (syn. A. rivieri), which has an edible corm (bulbo-tuber). It is also known as konjaku, konnyaku potato, devil's tongue, voodoo lily, snake palm, or elephant yam (though this name is also used for A. paeoniifolius).
It is native to Yunnan in China and cultivated in warm subtropical to tropical East and Southeast Asia, from Japan and China south to Indonesia (USDA hardiness zone 6-11). It is a perennial plant, growing from a large corm up to 25 cm (10 in) in diameter. The single leaf is up to 1.3 m (4 ft) across, bipinnate, and divided into numerous leaflets. The flowers are produced on a spathe enclosed by a dark purple spadix up to 55 cm (22 in) long.
The food made from the corm of this plant is widely known in English by its Japanese name, konnyaku (yam cake), being cooked and consumed primarily in Japan and Korea.