EQUATIONS FOR THE MOTION OF AIRBORNE POLLEN GRAINS NEAR THE OVULATE ORGANS OF WIND‐POLLINATED PLANTS

Abstract

A technique is presented that is capable of predicting the motion of airborne pollen grains and the probability of pollen capture by wind‐pollinated plants. Equations for the motion of rigid‐walled particles (= pollen grains, spores, or Sephadex beads) in a supporting, compressible fluid (= air) are derived from the first principles of fluid dynamics. These equations are incorporated into a computer program (MODEL) which can be used with a desktop computer. The operation of MODEL requires empirical data on the pattern of airflow or the motion of a pollen species around the surfaces of the taxonomically relevant ovulate plant organ. With this information, MODEL can predict the behavior of any pollen species for which physical properties (size and density) are specified or empirically known. The significance of this procedure lies in the quantification of physical phenomena that influence the mechanics and fluid dynamics of pollen capture in wind pollination. The technique is illustrated and tested by its application to two grass species (Setaria geniculata and Agrostis hiemalis) for which velocity fields of pollen motion have been previously reported.