<div>Figure
1. Midday foliage abscisic acid (ABA) level as leaf water potential
(Ψ<sub>l</sub>) declines during soil drought in angiosperm species<i>Umbellularia californica</i> (A) and conifer species <i>Callitris
rhomboidea</i> (B). Mean leaf water potential (Ψ<sub>l</sub>) at
turgor loss point and standard errors are shown as grey solid and dashed
lines vertical dashed grey line in A and B. Midday canopy conductance
during soil drought in <i>U. californica</i> (C) and <i>C.
rhomboidea</i> (D). Vertical dashed lines in C and D represent the
Ψ<sub>l</sub> at which peak foliage ABA level occurred. Generalized
additive model (GAM) curves and standard errors are represented in all
relationships by solid and dashed black lines, respectively.</div>