Cymodocea is a small genus of marine seagrasses in the family Cymodoceaceae, order Alismatales, described by K. D. Koenig in 1805 (published 1806). It comprises three accepted species: Cymodocea angustata, Cymodocea nodosa, and Cymodocea rotundata.
Species in the genus grow submerged in clear coastal water and in the high intertidal zone. Plants are generally hardy and can tolerate marginal growing conditions, but they cannot withstand full exposure at low tide or prolonged drying, which limits how far into the intertidal zone they can persist. Like other intertidal seagrasses, Cymodocea species can be difficult to distinguish from related genera in the field.
Collectively, the genus has a wide native distribution across warm seas: the Mediterranean (from Portugal to Israel, and Mediterranean Europe including Corsica, the Balearics, Greece, Albania, and Cyprus), the Atlantic coast of northwest Africa south to Senegal and the Canary Islands, the Red Sea and East African coast and islands (Egypt, Eritrea, Gambia, Comoros, Aldabra), and across the Indian Ocean and tropical Indo-Pacific (India, the Andaman Islands, Borneo, Hainan, the Caroline Islands and Bismarck Archipelago) as well as northwestern Australia. This range reflects the genus's occurrence as a foundational seagrass across tropical and warm-temperate coastlines.
Distribution
Cymodocea species occur across warm seas worldwide: C. nodosa in the Mediterranean (Portugal to Israel) and NW Africa to Senegal and the Canary Islands; C. rotundata across the Indian Ocean, Red Sea, South China Sea, and Pacific Ocean; and C. angustata in northwestern Australia. GBIF's World Checklist of Vascular Plants records native localities spanning the Mediterranean, East Africa/Indian Ocean islands, and the Indo-Pacific.
Ecology
Cymodocea grows in clear water and in the high intertidal zone. It is hardy and adaptable to marginal conditions but cannot tolerate full exposure at low tide or drying out, and can be readily confused with other intertidal seagrass species.
Taxonomy Notes
Cymodocea K.D.Koenig was described in 1805 (published in Annals of Botany 2: 96, 1806). It belongs to family Cymodoceaceae, order Alismatales, class Liliopsida. Three species are currently accepted.
