any of a diverse group of chiefly photosynthetic and aquatic plantlike organisms that range from unicellular to large multicellular forms, are typically classified as protists, and include the green, yellow-green, brown, golden-brown, and red algae in the eukaryotes and especially formerly the cyanobacteria in the prokaryotes

Note: While multicellular algae often resemble plants, they lack the true roots, leaves, and stems characteristic of vascular plants.

http://id.loc.gov/authorities/subjects/sh85003405

“Alga.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/alga. Accessed 15 Aug. 2026.