Of an algal stem or filament: composed of a single strand of large elongated cells. Of an alga: having filaments of this kind.

(a) belonging to the former class Rhodospermeae of algae (see rhodosperm n.); (b) having red seeds or spores (rare).

composed of or producing tetraspores.

composed of or producing tetraspores.

Of or belonging to the group Fucaceæ of seaweeds.

Botany. = monosiphonous, adj.

A thin, flat, brown seaweed of the genus so called; also known as oar-weed or kelp. Also attributive.

A calcareous, marine, red alga of the genus so called. Also attributive.