Abstract: Disclosed is a dendrometer for use on soft stemmed herbaceous plants. The dendrometer uses elongated jaws to engage the plant stem securely but without appreciable distortion or collapse of the stem. A transducer made of flexible, noncorrodible and temperature stable material spans between the jaws which engage the plant stem. Strain gauges are attached at appropriate locations on a transducer member and are connected to a voltage source and voltmeter to monitor changes in plant stem size. A microprocessor can be used to integrate the plant stem size information with other relevant environmental parameters and the data can be recorded on magnetic tape or used in other data processing equipment.