An agricultural machine includes a vibration stimulation source (160) configured to generate a vibration stimulation signal directed toward plant matter (104) and a sensor system (106) configured to sense electromagnetic radiation reflected from the plant matter (104), generate a first signal based on the sensed electromagnetic radiation, and generate a second signal indicative of a resonant vibration response of the plant matter (104), that is in response to the vibration stimulation signal. The agricultural machine includes a plant evaluation system (108) configured to, based on the first and second signals, generate plant (310) characterization data indicative of one or more physical characteristics (448) of the plant matter (104), and a control system configured to generate an action signal based on the plant (310) characterization data.
