Limu, otherwise known as rimu or ʻimu is a general Polynesian term for edible plants living underwater, such as seaweed, or plants living near water, like algae. In Hawaii, there are approximately one hundred names for kinds of limu, sixty of which can be matched with scientific names. Hundreds of species or marine algae were once found in Hawaii. Many limu are edible, and used in the cuisine throughout most of Polynesia.
Several species of limu are used as food throughout Polynesia and is typically eaten raw as accompaniment to meals, usually fish.
In Hawaii, limu was seen as a major component of the Hawaiian diet alongside fish and poi. Hawaiians cultivated several varieties of seaweed for food as well as to feed fish farmed within fish ponds. As many as 75 types of limu were used for food, more than the 35 used in Japanese cuisine, which is also well-known for its use of seaweed. In modern times, limu is often used as a condiment, typically in raw fish dishes such as poke.
Limu was used in hoʻoponopono, the ancient Hawaiian process of conflict resolution. Injured and accused parties gathered to pray, seek forgiveness and eat limu kala leaves as a symbol of reconciliation. It is also used in traditional hula attire and as medicine.
Due to the shape of its foliage, the Maori also applied the name rimu to the native tree Dacrydium cupressinum.
- Limu ‘ele‘ele (Enteromorpha prolifera)
- Limu kala (Sargassum echinocarpum) – employed during hoʻoponopono.
- Limu koele – "dry or hard"
- Limu a kohu (Asparagopsis taxiformis) – most popular
- Limu huluhulu waena (Grateloupia filicina or "pubic hair") – favorite of Liliʻuokalani.
- Limu hina (Hypnea spp.)
- Limu lipoa (Dictyopteris plagiogramma) – once found in almost continuous beds around O‘ahu. Disappeared from Waikiki Beach in the 1960s, crowded out by pollution and the invasive Gracilaria salicornia.
- Limu loloa (Gymnogongrus long or slender) 
- Limu manauea (Gracilaria coronopifolia, ogo [Japanese]) – cooked with meats to form a savory jelly. Later diced raw with poke, mixed with chili and salt.
- Limu palahalaha (Ulva fasciata) – used in hula
- Limu wawae‘iole (Codium edule)
- Pakaiea (green sea lettuce) – named after a shark god who was swaddled in its silken leaves.
- Lepelepe-o-Hina – shawl of the goddess Hina. Shares its name with a native butterfly and a family of nudibranchs.
- Kapoke whero (Gracilaria chilensis)
- Karengo (Pyropia spp.)
- Karepō (Zostera spp.)
- Rehia (Gigartina spp.)
- Rimurapa (Durvillaea antarctica)
- Rimurimu (Caulerpa brownii)
- Rimurimu kura (Polysiphonia spp.)
- Rimu akau (Sargassum spp.)
- Rimu kai (Caulerpa racemosa)
- Rimu oma (Hydroclathrus spp.)
- Rimu taratara (Turbinaria spp.)
- A ʻau (Halymenia spp.)
- Fuofua (Caulerpa racemosa)
- Limu aau (Gracilaria spp.)
- Limu lautalatala (Turbinaria spp.)
- Limu vaova (Sargassum spp.)
- Fuofua (Caulerpa peltata)
- Kaka (Caulerpa serrulata/Caulerpa cupressoides)
- Limu vai (Hypnea charoides)
- Louniu (Caulerpa sertularoides)
- Palalafa (Caulerpa scalpeliformis)
- Tangau (Cladosiphon spp.)
- Toke (Caulerpa racemosa)
Limu has become increasingly difficult to find because of over-picking, pollution, and urban development, especially construction in watersheds. Many important kinds of limu grow best in brackish water where fresh water empties into the sea. Another threat to limu is the spread of marine alien invasive species, such as members of the genus Kappaphycus (smothering seaweed), Gracilaria salicornia (gorilla ogo), Avrainvillea amadelpha (leather mudweed), Hypnea musciformis (hook weed) and Acanthophora spicifera (prickly seaweed).
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- Spalding, Heather. "Got limu? Uses for algae in Hawaii and beyond" (PDF). University of Hawaii. Retrieved April 25, 2019.
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