Spatial d/h heterogeneity of leaf water.

The mean deltaD value of petiole water of Pterocarpus indicus Willd (deltaD = -9.0 +/- 2.5 per thousand, n = 3) was not significantly different from the mean value of stem water (-8.3 +/- 2.8 per thousand, n = 3). deltaD values of main vein water ranged from -11.1 to + 12.0 per thousand (n = 14) and increased along the main vein from petiole to the tip of leaves. Mesophyll water was highly enriched in deuterium (mean deltaD = +32.0 +/- 2.0 per thousand, n = 19) when compared with stem, petiole, and vein water. deltaD values of mesophyll water for different areas of the lamina, however, were not homogenous and could differ by as much as 20 per thousand.