Movements of Helianthus annuus leaves and heads.
Diurnal movements of heads and leaves of sunflower cv. Hysun 30 were determined from 3-dimensional maps of the organs. Dirunal E.-W. oscillations of the heads occurred initially but ceased as the flowers opened and anthesis commenced, leaving the heads facing E. The amplitude of the leaf movements also diminished with time. The easterly aspect of the heads reduced the max. temp. of the florets; this may increase seed set.