We collected data at three sites in Washington Gulch near the Rocky Mountain Biological Laboratory (RMBL, Gothic, Colorado, USA) from June to August 2021 and 2022. RMBL is located in the East River valley of the West Elk mountains, approximately 10 kilometers from Crested Butte, Colorado. Study sites were located at 2815 m (38°53'50"N, 106°58'43"W), 3165 m (38°57'38"N, 107°01'53"W) and 3380 m (38°58'10"N, 107°01'53"W) in elevation. All sites are approximately 50 m2 and have similar slope and aspect (Sloat et al. 2015). We randomly defined five 1.2 m x 1.2 m plots within each site.
Within the plots, we marked all newly open flowering units once per week from early June to mid-August. We counted flowering units as either a single flower (most species), a flowering head (Asteraceae), or an umbel (Apiaceae). We only counted flowering units once as they opened, so counts were not cumulative. We quantified fitness as successful fruit and seed development at the end of the season. When flowers began to produce fruits, we counted the number of units with fruit, the number of developed fruits produced by each flowering unit, and the number of seeds per fruit. We also recorded the week of flowering for each fruit. We could not count fruits and seeds for all species because they disappeared, were consumed too quickly, or did not produce seeds during our field season.