Description given on Youtube:
Paul Andersen explains how plants use hormones to respond to their environment. The following hormones are detailed; auxin, cytokinins, gibberelins, abscisic acid and ethylene.
Intro Music Atribution
Title: I4dsong_loop_main.wav
Artist: CosmicD
Link to sound: http://www.freesound.org/people/CosmicD/sounds/72556/
Creative Commons Atribution License