(biology) Any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic.

plural of alga

Algal organisms viewed collectively or as a mass; algal growth. / (countable) A particular kind of algae.

(nonstandard) plural of alga / (nonstandard) plural of algae

plural of red alga

plural of green alga

Any of very many plant organisms, of the phyla Chlorophyta and Charophyta, that grow in damp places; a chlorophyte

Any algae of the phyla Rhodophyta, principally, and Glaucophyta, mostly reddish in colour.

Any of many seaweeds of the class Phaeophyceae.

plural of brown alga