An alkali-producing mechanism in macerated leaves

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Abstract
A pH rise to ca. 9.5 on washing the fiber of macerated leaves was observed in all spp. of the Cucurbitaceae examined and some members of the Urticaceae, Boraginaceae and Compositae. The rise was not prevented by heating and was speeded by fine grinding. ''Alkaline drift'' plants have a high Ca content, a large proportion of which is insoluble and occurs as CaCO3. The Ca cpntent of the fiber may be as high as 11% of the dry matter and the inorganic P content is also high, up to 1% of the dry matter. The Ca and P appear to be localized in and near the epidermal hairs. Young leaves in which have much lower contents of Ca and inorganic P do not show much pH rise. A pH rise to > 9 can be produced with ''non-drifter'' and acid-extracted ''drifter'' fiber and with pectic acid by soaking in neutral phosphate soln., washing and milling with CaCO3. After incubation of ''non-drifter'' fiber with polygalac-turonase the pH rise cannot be obtained.