Several different methods were investigated for storing conifer twigs and tree leaves for prolonged periods without changing their water status, as assessed by the pressure chamber. Whereas simple procedures (keeping between wet foam-rubber mats or even immersion in water) were sufficient for gymnosperms, the leaves of angiosperma had to be protected more carefully. With deciduous leaves the best method was to store them in completely airtight bags made from aluminium foil; sclerophyllous evergreen leaves may alternatively be covered with a layer of Vaseline and stored in polythene bags between wet foam-rubber sheets. It proved possible to keep leaves for periods of up to several days without significant changes in either their total water potential or their osmotic relations as determined by the pressure-volume technique.