Kenneth Vivian Thimann
Born August 5, 1904; died January 15, 1997 at the age of 92.
Anglo-American plant physiologist, pioneer in the field of plant physiology, in particular hormones which control the development of plants. In particular, he identified auxin, a growth hormone, and revealed its chemical structure. He also studied the biosynthesis of the pigments responsible for the colors of flowers and fruits, and the action of different areas of the light spectrum on photosynthesis. Later, he studied the factors controlling the mechanisms of plant senescence, in particular the aging of leaves.