Melanosperm

Me‐lan″o‐sperm (?), n. [Gr. μέλασ, -ανοσ, black + σπέρμα 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.