Teasel family (Dipsacaceae)
Fuller's teasel (Dipsacus fullonum) -- in March to August -- Saint Vrain State Park, CO blue & purple
Fuller's teasel (Dipsacus fullonum) -- in August -- Arapaho Bend, Fort Collins Natural Area, CO
Fuller's teasel (Dipsacus fullonum) -- in September -- Springer, Fort Collins Natural Area, Larimer County, CO
bluebuttons (Knautia arvensis) -- Bridal Veil Falls Trail, Rocky Mountain National Park blue & purple