Tripleurospermum maritimum Short-lived perennial or annual herb, 10-70 cm tall, usually with low, spreading branches, more or less unscented.
Leaves alternate. 2-8 cm long, twice pinnately divided, segments fleshy, linear, 0.2-0.5 cm long.
Flowers in heads 1.5-3 cm wide, ray flowers white, 12-25, 0.6-1.3 cm long, disk 0.8-1.5 cm wide, flowers yellow, 5-toothed, floral base (receptacle) rounded, no scales between disk flowers; inflorescence branched; blooms and fruits July-Oct.
Fruit dry 1-seeded achene with a short crown, body 3-ribbed, ribs nearly wing-like.
Wetland status: UPL.
Frequency in NYC: Very infrequent.
Habitat: Open sites, vacant lots, roadsides.
Notes: Listed as a noxious weed in WA and CO (USDA, NRCS 2010). See also Woo et al. (1991).