Porter (1981, Environ. Health Perspectives 37: 53-59) has
estimated that 2000 maize pollen grains weigh one milligram.
Miller (1982, In "Maize for Biological Research", WF Sheridan (ed),
pp. 279-293) reports a figure of 247 x 10 -9 g per pollen grain,
which is the equivalent of 4000 grains per mg.
Joseph P. Mascarenhas
Department of Biological Sciences
University at Albany, State University of New York
Albany, New York 12222