Limestone glades in Missouri are characterized by exposed bedrock, xeric conditions during much of the growing season, and a unique flora adapted to extremes of temperature and moisture. The Missouri bladderpod (Lesquerella filiformis Rollins) is a federally endangered plant species restricted to limestone glades within a narrow range of southwestern Missouri and northern Arkansas. Four populations of the Missouri bladderpod occur on limestone glades at Wilson's Creek National Battlefield, including a large population on Bloody Hill glade, where population size has been monitored since 1988. The size of the Missouri bladderpod population on Bloody Hill fluctuates dramatically from year to year. One causative factor may be differences in plant survivorship among the glade habitats where it grows. An automated weather station was installed on North Bloody Hill glade (0.44 km North of the Bloody Hill population) to measure air temperature, relative humidity, solar radiation, precipitation, wind speed and direction, snow depth, soil temperature and moisture, and fuel temperature and moisture. Climate monitoring on North Bloody Hill glade in 1996 and 1997 has documented an extreme temperature environment on the glade and differences in soil temperature and moisture levels among glade habitats. Microclimate differences among glade habitats may partially account for differences in germination and survival of the Missouri bladderpod. Furthermore, a preliminary analysis of climate variables indicates the precipitation in May of the previous year may be a significant predictor of Missouri bladderpod population size.