Lesquerella ludoviciana (Nutt.) S. Wats. (silvery bladderpod) (Brassicaceae) is an endangered plant of Illinois sand prairies, where natural populations occur only in the Henry Allen Gleason Nature Preserve (Mason County). Flowers bloom in spring. Both self and cross-pollination occurs within other Lesquerella species. Objectives were to determine how photoperiod affects flower development and whether flowers are self or cross-pollinated. Seeds were collected from the Nature Preserve and grown in greenhouses. For photoperiod studies, fifteen plants each were placed in long (sixteen hours) and short (eight hours) days in greenhouses. Number of inflorescences and number of open flowers were recorded weekly for 15 weeks. For pollination studies, flower stalks were manipulated with self-pollination or cross-pollination, emasculation or no emasculation, and bagged or not bagged (2 x 2 x 2), with two replications of each combination. Pollination was considered successful if fruit developed. Plants developed inflorescences after 20 and 28 days in the long and short photoperiod, respectively. Number of inflorescences/plant increased steadily for both photoperiods throughout the 15 weeks. Plants in short days produced more inflorescences (10.8 per plant) compared to those in long day (7.2 per plant). Long day plants had open flowers starting at 41 days relative to 56 days for short day plants. Bloom peaked at 4.9 flowers/plant/day at 83 days in long days, and at 3.5 flowers/plant/day at 98 days in short days. The most successful pollination method was cross-pollination with no emasculation and not bagged flower stalks. Photoperiod was determined not to be a requirement for flower initiation, but affected flower development. Short day plants developed more inflorescences, but did not necessarily produce fully developed flowers compared to long day plants. Plants appeared to be self-incompatible.

Key words: Brassicaceae, endangered plant, photoperiod, pollination, sand prairie