Hypoglossum hypoglossoides, known as under tongue weed, is a small red marine alga in the family Delesseriaceae.
Hypoglossum hypoglossoides is a small red alga growing as monostromatic blades in tufts to a length of 30 cm and 0.8 cm wide. The lateral branches grow as blades which, like the primary blade, has a midrib. All the blades have a lanceolate or acute apices. All the blades lack lateral veins.[1] [2]
The plants are dioecious. Spermatangial sori are formed on the blades on either side of the midrib. Cystocarps develop singly on the blades.[1]
Found in the littoral and sublittoral on rock or epiphytically on other large algae.[3]
Found on the shores of Ireland, Great Britain, Isle of Man and the Channel Islands. Further south in Spain and the Mediterranean, as well as North Carolina to Brazil.[1]