Leaves of Pinus ponderosa retained more moisture when attached to cut branches than did those of Pseudotsuga taxifolia, Pinus monticola Thuja plicata, Abies grandis, or Picea engelmanni. When leaves were removed from branches and dried in laboratory, Pinus ponderosa and Pseudotsuga taxifolia retained more moisture than the other spp. Pinus monticola and T. plicata retained more moisture than A. grandis or Picea engelmanni. Rehydration of needles after periods of drying of from 2-12 days and testing for viability with 2,3,5-triphenyltetrazolium chloride showed that a loss of leaf moisture below about 50% of the dry weight results in death.