y=f(m,t)c+g(m,t) for the first time. A mechanism on the information transmission of the nutrition growth in plants was discussed by the math language. The bark and timber at a stem of plants could be derived from phloem and xylem cells respectively because the wave period of electric signals’ c in cambium cells was rather short and needed to transfer the growth information of cells to the circumference rapidly. It was why the wave period of electric signals at the cambium of plants was shorter than the phloem and xylem. Only positive amplitude value of electric signals of the xylem was bigger than the phloem and cambium, which expressed the needed more energies for the elongated growth up of plants. An importance is that the discovery in this paper may find out the character preferences for constructing a system of the intelligent control growth by feedback information at the transmission of the signals in plants or crops, and to realize the energy saving and pollutant abating to environments.