\Des"mid\, Desmidian \Des*mid"i*an\, n. [Gr. desmo`s
chain + e'i^dos form.] (Bot.)
A microscopic plant of the family {Desmidi[ae]}, a group of
unicellular alg[ae] in which the species have a greenish
color, and the cells generally appear as if they consisted of
two coalescing halves.