Lythrum hyssopifolia.en.wikipedia.org (Accessed 4/2014).

Lythrum hyssopifolia is an annual herb 10-60 cm tall, pale green, stem 4-angled. 

Leaves mostly alternate, stalkless, blade 1-3 cm long, 0.1-0.7 cm wide, linear to elliptic. 

Flowers pale purple, radially symmetrical, petals 4-6, 0.2-0.3 cm long, wedge-shaped (cuneate); calyx tubular, lobes 4-6, short; appendages between calyx lobes longer than lobes; stamens 4-6, shorter than calyx tube; flowers 1-2 in leaf axils; blooms and fruits June-Sept. 

Fruit a dry capsule. 

Wetland status: OBL. 

Frequency in NYC: Very infrequent.. 

Origin: Europe. 

Habitat: Brackish marshes.