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Leaf water relations characteristics of creosote bush, Larrea tridentata, were studied in view of previous reports that its leaves commonly experience zero or negative turgor under dry conditions. Leaf turgor loss point (ψzπ) was determined by a pressure-volume method for samples subjected to a hydration procedure and for untreated samples. Hydration caused ψzπ to increase by as much as 3 MPa. Hydration of samples also caused changes in other leaf water relations characteristics such as symplastic solute content, tissue elasticity and symplasmic water fraction, but total leaf solute content was unchanged. Comparison of our field plant water potential data with values of ψzπ obtained by the two methods resulted in predictions of turgor loss during part or all of a diurnal cycle based on hydrated samples, and turgor maintenance (at least 0.3 MPa) based on untreated samples. Pooled data for ψzπ obtained from both partially hydrated and untreated samples showed that L. tridentata maintains fairly constant levels of turgor over a wide range of leaf water potential. Dilution of cell contents by apoplastic water introduced significant errors in psychrometric determinations of osmotic potential in both frozen and thawed leaf tissue and expressed cell sap. Use of these values of osmotic potential resulted in predictions of zero turgor at all plant water potentials measured in the field. [ABSTRACT FROM AUTHOR]