Information about life history and threats to survival of the threatened plant, purple amole (Chlorogalum purpureum var. purpureum), is unknown. From 1998 to 2004, monitoring programs were established across 23 sites at Fort Hunter Liggett, California, to characterize: i) flowering, seed production, and persistence of purple amole and ii) the relationship of purple amole density to associated vegetation and disturbance. Our objective was to summarize these data and complete a power analysis to determine the ability of future monitoring efforts to detect significant upward or downward trends of purple amole populations over time. Overall, purple amole was most likely to flower and have greater seed production when it attained approximately 8 leaves or widths of 7 to 8 mm for its widest leaf, revealing a clear relationship between size of purple amole and successful reproduction and seed set. Dormancy was common, often exceeding one year and extending to at least four years. Of individuals monitored from 1998 through 2004, 23 ± 2.9% exhibited dormancy. Mortality rate per year was estimated at 10%. A positive correlation (P °Ü 0.05) was found between density of purple amole and cover of native species (r = 0.20) and presence of biological soil crusts (r = 0.27). Averaged across plots and years, mean cover of total herbaceous species was 67 ± 1.9%. Of this cover, 21 ± 1.3% were native species and 51 ± 2.5% were non-native species. Biological soil crusts occurred in 50 ± 3.7% of the plots. In future monitoring efforts, the ability to detect significant upward or downward trends in abundance will depend on the size of purple amole plants, number of years the populations are monitored, the rate of change to be detected, and whether trends are linear or exponential.