Oscillations in sap flux in two branches of a plant were found to be non-synchronous but frequently phase-locked, even though the branches had very different energy budgets. Time lags in the transmission of oscillations along a stem were measured, and analysed in terms of an electrical transmission-line analogy. The equivalent ‘circuit elements’ in the stem were identified and their values calculated. These values were used to derive the expected time lags of oscillations along a stem. Derived values agreed closely with those measured.