Phyllotaxy and water relations in tobacco.

The relative effectiveness of vascular connections between adjacent leaves of tobacco is demonstrated. It is shown that water movement between adjacent leaves is more difficult than between phyllotactically related leaves. Total and specific resistance ratios between adjacent and phyllotactically related leaves are calculated. These figures indicate that vertical water potential profiles need to be interpreted with a full knowledge of the vascular structure and phyllotaxy as well as gross structural and environmental parameters.