- Usually bluets. Also called innocence, Quaker-ladies. any of several North American plants of the genus Houstonia (or Hedyotis), of the madder family, especially H. caerulea, a low-growing plant having four-petaled blue and white flowers.
- any of various other plants having blue flowers.
- a North American rubiaceous plant, Houstonia caerulea, with small four-petalled blue flowers