Melanosperm \Me*lan"o*sperm\, n. [Gr. me`las, me`lanos, black +
spe`rma seed.] (Bot.)
An alga of any kind that produces blackish spores, or seed
dust. The melanosperms include the rockweeds and all kinds of
kelp. -- {Mel`a*no*sper"mous}, a.
[1913 Webster]