Meristotheca papulosa (synonyms: M. japonica and Eucheuma papulosa) is a red alga, popular as a sea vegetable in Taiwan, where it is known as jiguancai and in Japan, where it is known as tosaka-nori (トサカノリ).
It has isomorphic alternation of generations (the sporophyte and the gametophyte share a very similar appearance). The tetrasporangia are divided in a ladder shape and scattered across the cortex.
It is very widely distributed along the coasts of the Indian Ocean from South Africa to Australia, and the western Pacific Ocean from Australia to Japan.