A Key to the Species of Halophila (Hydrocharitaceae), with Descriptions of the American Species

During the revision of the Hydrocharitaceous genus Halophila for the Flora Malesiana it appeared for nomenclatural reasons necessary to study the genus in its entirety. In this Flora (Den Hartog, 1957b) I have already accounted for the Malaysian species. In that paper I have also included H. slipulacea (Forsk.) Aschers. which is commonly distributed in the western part of the Indian Ocean and the Red Sea and has immigrated in recent years via the Suez Canal into the eastern Mediterranean. A new species, H. linearis Hartog, I have described (Den Hartog, 1957a) from Portuguese East Africa. The remaining American species, all occurring in the Caribbean, will be treated in this paper. In order to facilitate the study of this interesting marine genus a key to all species has been prepared.