Symphyotrichum tenuifolium is a perennial herb, 20-70 cm tall, stems zigzag, plants colonial from a thin rhizome.
Leaves alternate, few, 4-15 cm long, 0.1-0.5 cm wide, linear, fleshy, reduced upwards to bracts, the lower soon deciduous.
Flowers tubular, of two types; ray flowers 15-25, blue to pink, 0.4-0.7 cm long, in heads with basal bracts (involucre) 0.6-0.9 cm long, bracts membranous, tips sometimes greenish, inner bracts often purplish; inflorescence branched, heads solitary, on stalks with small, linear bracts.
Wetland status: OBL.
Frequency in NYC: Infrequent.
Habitat: Salt marshes, quiet tidal areas.