Figure 10.28: The hormone ethylene plays a role in signaling these flower petals to separate
and drop, a process known as abscission. ( 24 )
seeds and buds. Gibberellins signal that it’s time for a seed to germinate or for a bud to
open.
Figure 10.29: Dwarf plants like this bonsai tree often have unusually low concentrations of
gibberellins. ( 22 )
Cytokininsare hormones that promote cell division. Cytokinins were discovered from
attempts to grow plant tissue in artificial media (Figure10.30). Cytokinins also prevent
senescence,the programmed aging process. As a result, florists sometimes apply cytokinins