Table III. Symbols, terms, units, derivation, and biological significance of the nine key leaf thickness and area shrinkage traits in this study.

An additional nine traits were quantified, and their calculation and correlations with these key traits are described in Supplemental Materials and Methods S1, Supplemental Results S1, and Supplemental Tables S2 to S4.

Symbols	Parameters	Units	Derivation	Significance
Thickness shrinkage
PLTleaf,TLP	Percentage loss of thickness at TLP	%	From plot of PLT versus Ψleafa	Estimate of leaf thickness shrinkage at TLP
PLTC,TLP	Percentage loss of cell thickness at TLP	%	From plot of PLTC,TLP versus Ψleafa	Estimate of the amount of cell thickness lost when cells become flaccid
PLTA,TLP	Proportion of intercellular airspace thickness lost at TLP	%	From plot of PLTA,TLP versus Ψleafa	Estimate of the amount of airspace thickness lost (or gained) when cells become flaccid
dTleaf/dΨ	Degree of shrinkage of leaf thickness	% MPa−1		Steepness of the decline of whole-leaf thickness with Ψleaf before cells become flaccid
dTC/dΨ	Degree of shrinkage of leaf cells	% MPa−1		Steepness of the decline of cell thickness with Ψleaf before cells become flaccid
dTA/dΨ	Degree of shrinkage of leaf intercellular airspace	% MPa−1		Steepness of the decline of air thickness with Ψleaf before cells become flaccid
PLTdry	Percentage loss of thickness in a dry leaf	%		Maximum amount of thickness shrinkage
Area shrinkage
PLAleaf,TLP	Percentage loss of area at TLP	%	From plot of PLA versus Ψleafa	Estimate of leaf area shrinkage at TLP
PLAdry	Percentage loss of area in a dry leaf	%		Maximum amount of area shrinkage

^aBecause thickness of the leaf or tissues precisely at TLP could not be determined, we interpolated the value for TLP by assuming a linear decline of leaf dimensions with Ψ_leaf between the two surrounding measurements.