1
general::
Become established or fixed, as in We're not sure how the movement took root, but it did so very rapidly. This idiom transfers the establishment of a plant, whose roots settle into the earth, to other matters. [Late 1500s]
American Heritage Idioms
2
general::
Phrase(s): take root
1. Lit. [for a plant] to develop roots in soil or some other growing medium. • The new plants should take root in a few weeks and start growing. 2. Fig. to begin to take hold or have effect. • Things will begin to change when my new policies take root. • My ideas began to take root and inf luence other people.
McGrawhill's American Idioms And Phrasal Verbs