cush-cush yam (English spelling) cushcushyam

…It is widely distributed in the wild in the tropics, but was probably introduced by humans. (7) As with the cashew, there are other species that are either abandoned in cultivation or of little importance today, such as the cush-cush yam, D. trifida L. (native to northern South America), whose leaves are divided into three lobules, and D. pentaphylla L. (native to tropical Asia), whose leaves are divided into five lobules. There are also over 60 wild species of Dioscorea that are used for food.
[Wild species in Japan]
D. tokoro Makino (Chinese name: Shanbou) has a horizontal underground stem with root hairs, and the leaves are alternate, triangular cordate, thin, and have wavy leaf edges.

*Some of the terminology that mentions "cush-cush yam" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…広く熱帯に野生状態で分布するが，人間が持ち込んだものであろう。(7)カシュウイモと同様に，現在は栽培が放棄されているか重要でないものに，葉が3小葉に切れ込むミツバドコロD.trifida L.(英名cush‐cush yam)(南米北部原産)，5小葉に切れこむアケビドコロD.pentaphylla L.(熱帯アジア原産)などがあり，またヤマノイモ属の野生種で食用に供されているものは60種をこえる。
［日本の野生種］
　トコロ(オニドコロ)D.tokoro Makino(中国名は山萆薢)は横走し，ひげ根を有する地下茎を有し，葉は互生，三角状心形で質は薄く，葉縁は波うつ。…

※「cush-cush yam」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報