The principal alterations to be mentioned under this head may therefore be conveniently arranged under the following categories:—Union, Independence, Displacement, Prolification, Heterotaxy, and Heterogamy.

This circumstance is more fully treated of in the succeeding chapter relating to Heterotaxy.

For other cases of prolification or the adventitious formation of buds on leaves, roots, &c., see under Heterotaxy.