There is no simple definition of the term “domestication.” […] As in animals, in its most extreme form plant domestication ends up with species which cannot reproduce by themselves and which are therefore without wild populations. […] It is no accident that all important food plants of the world belong in this category of totally captive populations, since the reduction of the ability to self-reproduce has resulted in greatly increased food values in the plants concerned.
Michael D. Coe and Rex Koontz, Mexico: From the Olmecs to the Aztecs, Sixth Edition p27