A device for collecting plant samples includes a punch and die mechanism for taking leaf plugs from plants. The punch itself includes a punch rod coaxially mounted inside a punch tube. In use, the punch tube has a distal end with two, diametrically opposed projections that interact with the formed aperture to cut a plug from a plant leaf. The punch rod then follows to remove a cut leaf plug from the formed aperture. Also included is a hydraulic subsystem for periodically delivering liquid on the punch and die mechanism to prevent plant debris from clogging the device.