Leaves sessile, alternate, to 3.5 cm long, 3-veined, narrowly lance-shaped.
Flowers blue, radially symmetrical, petals 5, to 2.3 cm long, tip blunt, base narrowed on long stalks, May-July.
Fruit a dry, rounded capsule to 0.9 cm wide, opening into 10 segments to release one seed from each segment.
Wetland status: UPL.
Frequency in NYC: Very infrequent.
Habitat: Disturbed, open habitats.
Notes: The source of linen fiber and of flaxseed oil.