Konnyaku (Amorphophallus konjac; English: konjac; Japanese: konnyaku; Korean: ; gonyak; Chinese: ; pinyin: j ru) is a type of tuber plant belonging to the genus Amorphophallus that grows in areas warm subtropical to tropical such as East Asia, Japan, southern China to Indonesia. Other names in foreign languages are konjac, konjaku, devil's tongue, or elephant foot yam (although this last name is also assigned to suweg A. paeoniifolius)

Konnyaku is an annual plant that grows from large tubers with a diameter of 25 cm. This tuber is a modification of the stem. The leaves measure 1.3 m from the base, pinnate, and divided into various leaflets. The flowers are produced in a flower sheath (spatha) protected by a dark purple protective leaf (bractea) measuring up to 55 cm.