Water Movement Into and Through Tradescantia virginiana (L.) Leaves: II. LIQUID FLOW PATHWAYS AND EVAPORATIVE SITES

Excised leaves of T. virginiana were supplied at their baseswith water containing a dilute solution of lead-EDTA chelate.After the leaf had been allowed to transpire for 3–5 hthe lead was precipitated in situ using hydrogen sulphide. Leafsections were examined microscopically and the path of the transpirationstream and the sites of evaporation inferred from the distributionof lead precipitate. From the distribution of precipitate itwas concluded that there is more evaporation from cells liningthe substomatal cavity, compared with cells in the bulk of themesophyll, than was previously thought to be the case.