ANISO (from anisos, unequal), a prefix to several terms in natural history, implying some kind or degree of inequality of parts: as, for example, aniso-dactylous birds, i.e., having toes of unequal length; aniso-dynamous plants, i.e., having flowers which grow with more vigour on one side of their axis than on the other; aniso-stemonous flowers, i.e., having a greater or a less number of stamens than there are sepals in the calyx.