Then the pedicels of the umbels bearing only staminate flowers elongate, so that these flowers stand over the hermaphrodite flowers with their mature stigmas, and their anthers release pollen that falls upon the stigmas below. Apparently, both nectar and pollen are produced by the flowers. The early flowers are dependent upon pollen brought to them from other plants. Later flowers receive pollen by gravity from the anthers above them. Self-fertilization within a flower is impossible.
Gravity also contributes to the pollination.
The agitation of the flowers by the insects can contribute to the rain of pollen on the stigmas below. Pollination Recommendations and Practices None, probably because of the small acreage necessary to produce the required seed. Large plantings would doubtless benefit if bees were plentiful within the field. Lea and Febiger, Philidelphia. U. S. Dept.