figure

Figure 16.14 Representation of uptake, transport and partitioning of  the phloem-mobile and xylem-tapping nutrient potassium (K+) between a tree host and a xylem-tapping mistletoe. K taken up from soil (1) moves to the host shoot (2) and across the lumen-to-lumen xylem continuities (7) and parenchyma (8) of the haustorial interface and thence into the mistletoe (10). K in the host shoot is then pictured as being retained in host biomass (MH), lost through leaching by rain (5), in organ shedding (5) or cycled back to the root via phloem (4). Similar accumulation (MP) and cycling (items 11-14) are depicted for the mistletoe but with no backflow to the host. The mistletoe runs at an 'excess' of K due to a higher rate of transpiration and markedly active absorption of K by parenchyma of the hasutorial interface. Foliage shed by mistletoes is still fully loaded with K. (Based on Pate 1995)