Movements of Helianthus annuus Leaves and Heads

Abstract

Diurnal movements of heads and leaves of sunflower (H. annuus cv Hysun 30) were determined from 3-dimensional maps of the organs. Diurnal E-W [east-west] oscillations of the heads occurred initially but ceased as the flowers opened and anthesis commenced, leaving the heads facing east. The amplitude of the leaf movements also diminished with time. The easterly aspect of the heads reduced the maximum temperature of the florets; this may increase seed set.