From WordNet (r) 3.0 (2006) [wn]:
algae
n 1: primitive chlorophyll-containing mainly aquatic eukaryotic
organisms lacking true stems and roots and leaves [syn:
alga, algae]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
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]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
algae \algae\ n.
plural of alga.
[WordNet 1.5]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
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