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).
Color varies from red to peach. Texture is fleshy and cartilaginous. Shape is flat and leaf-like, with irregular deep forking divisions. The edges often grow many branchlets of uneven lengths. The surfaces of older individuals will grow warty or spiky protuberances. The morphology is variable. Length can reach 10-40 cm, branch width 1-5 cm. The interior of the algal body is multi-axised.
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.
Ecology and distribution
It grows on subtidal rocks 5-20 metres
deep, and can be seen at all times of the year.
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.