Which root vegetable is called renkon in tempura ingredient lists?

The root vegetable called renkon in tempura ingredient lists is lotus root.

Renkon is the Japanese name for the edible rhizome of the lotus plant. Sliced crosswise, it reveals a distinctive pattern of holes, which remains visible after coating and frying. Its firm, slightly crisp texture makes it a popular vegetable-tempura ingredient.

Tempura developed in Japan after Portuguese-influenced frying techniques arrived in the 16th century, then evolved through Edo-period food-stall culture. Renkon is one of many vegetables used in yasai tempura, alongside kabocha squash, sweet potato, eggplant, mushrooms and shiso.

A common mix-up is treating lotus root as an ordinary root vegetable. Botanically, it is a rhizome—an underground stem—but “lotus root” is the standard culinary name. It is often served with tentsuyu dipping sauce or grated daikon.