Polygala cruciata is an annual herb to 30 cm tall, branches few or none.
Leaves in whorls or 3-4, linear, to 4 cm long, 0.5 cm wide, often widest above middle, tip blunt.
Flowers purplish, irregular, to 0.6 cm in a dense spike-like, cylindrical cluster to 6 cm long, 1.5 cm wide, at top of plant; blooming July-Sept.
Wetland status: FACW+.
Frequency in NYC: Very infrequent.
Habitat: A pine-barrens bog plant.