From The Collaborative International Dictionary of English v.0.48 :
Malvaceous \Mal*va"ceous\, a. [L. malvaceus, from malva mallows.
See Mallow.] (Bot.)
Pertaining to, or resembling, a natural family of plants
({Malvaceae), of which the mallow is the type. The cotton
plant, hollyhock, and abutilon are of this family. It was
formerly classified as an order, and included the baobab and
the silk-cotton trees. The baobab and silk-cotton trees are
now placed in the family Bombacaceae, which is included
with the Malvaceae in the order Malvales.
[1913 Webster +PJC]