Houstonia caerulea is a very small, delicate winter annual or perennial herb, 5-10 cm tall in flower, winter rosettes forming mats a few cm wide, colonial by slender rhizomes.
Leaves opposite mostly basal, widest above middle, ca 1 cm long, stalk ca 1 cm; stem leaves reduced, nearly stalkless (subsessile).
Flowers pale blue with yellow eye, to 1 cm long, 1-1.4 cm wide, radially symmetrical, tubular with spreading 4 petal lobes, ovary inferior, flowers solitary in leaf axils on stalks to 7 cm tall, styles of two different lengths (distylous), self-incompatible (Hicks et al. 1985); blooms April-June. Most likely pollinated by insects (Proctor et al. 1996).
Fruit dry, paired capsules 0.3-0.4 cm wide, flattened, broader than long, splitting open to release minute, rounded seeds with a cavity on one side.
Wetland status: FACU.
Frequency in NYC: Very infrequent.
Habitat: A woodland plant.