Non invasive measurements avoid physical-chemical interference with, entrance to, or reaction with the analyte, intervening with its normal behavior. Optical remote monitoring of biological tissues, as plant leaves, allows a non invasive measurement because there is no physical contact between the sensor and the leaf, resulting in no interference with the normal behavior of the plant. Previous the monitoring, it is needed the characterization of the analytes for selecting the wavelength where the tissue has the most quantifiable response. In this document are presented the optical absorption characterization results of different plants in the ranges of Ultra Violet, Visible, Near IR, and Medium IR. Some possible monitoring applications of such characterization are: physiological research, detection of diseases and production forecasting.