Houstonia genus --- madder family
bluets (Houstonia caerulea) -- in April -- Natchez Trace Parkway, southern Tennessee           white & cream     
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bluets (Houstonia caerulea) -- in July -- Acadia National Park, Maine                  
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small bluet (Houstonia pusilla) -- in April -- Natchez Trace Parkway, southern Tennessee           white & cream