Some observations on the floral biology of the carrot (Daucus carota L.)

The production of carrot seed sometimes presents the problem of the occurrence of seedless umbels. During an investigation into the cause of this phenomenon, a number of floral-biological data have been collected which are valuable both for the seed production and breeding of this crop.

1. 1.
   The distribution of male flowers and bisexual flowers. Both in the wild carrot and in 2 cultivated varieties the tendency to produce male flowers was encountered. In all forms tested the percentage of male flowers was practically negligible in the main umbel and was found to increase regularly in umbels of higher order. There were, however, clear differences in the mean percentage between the forms tested. Presumably the tendency to produce male flowers is determined genetically, but it may also be affected by the environment.