Word Study
florideæ
CIDE DICTIONARY
florideæ, n. pl. [NL., from L. flos, floris, a flower.].
A subclass of algæ including all the red or purplish seaweeds; the Rhodospermeæ of many authors; -- so called from the rosy or florid color of most of the species. [1913 Webster]
For further exploring for "florideæ" in Webster Dictionary Online