3.5 Hydathode-mediated foliar water uptake
The results of the experiment showed that FWU could be induced in drought-stressed plants of all but one (i.e. C. perforata )Crassula species examined (Fig. 8 ). In all species in which FWU could be induced, well-watered plants showed no or very little uptake of the tracer compared with drought-stressed plants. In all species that absorbed the tracer, LYCH fluorescence could be detected in the hydathodes of the leaf surface exposed to the tracer, in most vascular bundles within the leaf, and even in the hydathodes of surfaces that were not exposed to the tracer, which indicates efficient redistribution of absorbed water. Varying degrees of tracer fluorescence were also observed in the indumentum of several species. The redistribution of absorbed water within the leaves was most noticeable in the two species with planar leaves, given that they were easier to image (Fig. 9 ).