(from δις, twice, and οἶκος, a house or habitation) two houses; the name of the 22d clas in Linnaeus's sexual method, consisting of plants which having no hermaphrodite flowers, produce male and female flowers on separate roots. These latter only ripen seeds; but require for that purpose, according to the sexualists, the vicinity of a male plant; or the affusion, that is, sprinkling of the male dust. From the seeds of the female flowers are raised both male and female plants. The plants then in the clas dioecia are all male and female; not hermaphrodite, as in the greater number of classes; nor with male and female flowers upon one root, as in the clas montecia of the same author. See BOTANY Index.