Gametophytes of the liverwort Marchantia polymorpha contain both absci
sic acid and 2-trans-abscisic acid in a 1.2:1 ratio. Abscisic acid is
present in concentrations similar to those in higher plants. Indole-3-
acetic acid was also detected. This is the first chemical demonstratio
n that ABA and its 2-trans-isomer occur in the Hepatophyta.