Figure 4 . Relationship between inferred boundary layer conductance to heat (g bh) and time constant for leaf cooling (τ ) for leaf patches. Colors indicate species; small, solid symbols denote hairy patches, and large, semitransparent symbols denote bald patches. Variation in the relationship of estimatedg bh to the measured τ within each species arises from differences in leaf heat capacity and stomatal conductance among leaves.