Petaloideous \Pet`al*oid"e*ous\, a. (Bot.) Having the whole or part of the perianth petaline. {Petaloideous division}, that division of endogenous plants in which the perianth is wholly or partly petaline, embracing the {Liliace[ae]}, {Orchidace[ae]}, {Amaryllide[ae]}, etc.