The Collaborative International Dictionary of English v.0.48:
Rhodosperm \Rho"do*sperm\, n. [Gr. "ro`don the rose + spe`rma a seed.] (Bot.) Any seaweed with red spores. [1913 Webster] Note: As the name of a subclass, Rhodosperms, or Rhodospermeae, is synonymous with Florideae (which see.) [1913 Webster]