Alga \Al"ga\, n.; pl. Alg[ae] or algae. [L., seaweed.]

(Bot.) A kind of seaweed; pl. the class of cellular cryptogamic plants which includes the black, red, and green seaweeds, as kelp, dulse, sea lettuce, also marine and fresh water conferv[ae], etc. The algae are primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves. [1913 Webster + WordNet 1.5]

Source: The Collaborative International Dictionary of English v.0.48
 

algae \algae\ n. plural of alga. [WordNet 1.5]

Source: The Collaborative International Dictionary of English v.0.48
 

Cryptogamia \Cryp`to*ga"mi*a\ (kr?p`t?-g?"m?-?), n.; pl. Cryptogami[ae] (-?). [NL., fr. Gr. krypto`s hidden, secret + ga`mos marriage.]

(Bot.) The series or division of flowerless plants, or those never having true stamens and pistils, but propagated by spores of various kinds. [1913 Webster]

Note: The subdivisions have been variously arranged. The following arrangement recognizes four classes: -- I. {Pteridophyta, or Vascular Acrogens.} These include Ferns, Equiseta or Scouring rushes, Lycopodiace[ae] or Club mosses, Selaginelle[ae], and several other smaller orders. Here belonged also the extinct coal plants called Lepidodendron, Sigillaria, and Calamites. II. {Bryophita, or Cellular Acrogens}. These include Musci, or Mosses, Hepatic[ae], or Scale mosses and Liverworts, and possibly Charace[ae], the Stoneworts. III. {Alg[ae]}, which are divided into Floride[ae], the Red Seaweeds, and the orders Dictyote[ae], Oospore[ae], Zoospore[ae], Conjugat[ae], Diatomace[ae], and Cryptophyce[ae]. IV. {Fungi}. The molds, mildews, mushrooms, puffballs, etc., which are variously grouped into several subclasses and many orders. The Lichenes or Lichens are now considered to be of a mixed nature, each plant partly a Fungus and partly an Alga. [1913 Webster] Cryptogamic Cryptogamian

Source: The Collaborative International Dictionary of English v.0.48
 

67 Moby Thesaurus words for "algae": Ectocarpales, Iceland moss, Irish moss, Phaeophyceae, autophyte, bean, bracken, brown algae, climber, conferva, confervoid, creeper, diatom, dulse, fern, fruits and vegetables, fucoid, fucus, fungi, fungus, grapevine, green algae, gulfweed, herb, heterophyte, ivy, kelp, legume, lentil, liana, lichen, liverwort, mold, molds, moss, mushroom, parasite, parasitic plant, pea, perthophyte, phytoplankton, plankton, planktonic algae, plant families, pond scum, puffball, pulse, red algae, reindeer moss, rockweed, rust, saprophyte, sargasso, sargassum, scum, sea lentil, sea moss, sea wrack, seaweed, smut, succulent, thallogens, toadstool, vetch, vine, wort, wrack

Source: Moby Thesaurus II by Grady Ward, 1.0
 

algae

Source: WordNet (r) 2.0
 

Alga \Al"ga\, n.; pl. Alg[ae]. [L., seaweed.]

(Bot.) A kind of seaweed; pl. the class of cellular cryptogamic plants which includes the black, red, and green seaweeds, as kelp, dulse, sea lettuce, also marine and fresh water conferv[ae], etc.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Cryptogamia \Cryp`to*ga"mi*a\ (kr?p`t?-g?"m?-?), n.; pl. Cryptogami[ae] (-?). [NL., fr. Gr. krypto`s hidden, secret + ga`mos marriage.]

(Bot.) The series or division of flowerless plants, or those never having true stamens and pistils, but propagated by spores of various kinds.

Note: The subdivisions have been variously arranged. The following arrangement recognizes four classes: -- I. {Pteridophyta, or Vascular Acrogens.} These include Ferns, Equiseta or Scouring rushes, Lycopodiace[ae] or Club mosses, Selaginelle[ae], and several other smaller orders. Here belonged also the extinct coal plants called Lepidodendron, Sigillaria, and Calamites. II. {Bryophita, or Cellular Acrogens}. These include Musci, or Mosses, Hepatic[ae], or Scale mosses and Liverworts, and possibly Charace[ae], the Stoneworts. III. {Alg[ae]}, which are divided into Floride[ae], the Red Seaweeds, and the orders Dictyote[ae], O["o]spore[ae], Zo["o]spore[ae], Conjugat[ae], Diatomace[ae], and Cryptophyce[ae]. IV. {Fungi}. The molds, mildews, mushrooms, puffballs, etc., which are variously grouped into several subclasses and many orders. The Lichenes or Lichens are now considered to be of a mixed nature, each plant partly a Fungus and partly an Alga.

Source: Webster's Revised Unabridged Dictionary (1913)