A sampling tool includes a guiding body provided with a through bore, and a part-carrying punch mounted slidingly adjustable in the bore having a lower edge forming a cutting edge. A part-carrying die of the tool is provided with a cutting upper edge and separated from the guiding body by an opening provided with a through bore which the lower end of the punch enters when cutting the sample to be collected. An actuator to actuate the punch between an initial position, a stationary intermediate position, and a final position in which the punch passes through the die. The path of the punch is tangential to the surface of the opening and the bore is tangential to a geometric plane containing the surface to make a cut with an open contour in the plant from which the sample is collected.
