Coronopus didymus is an annual or biennial, fetid smelling herb 10-40 cm tall, forming mats to 80 cm wide, stems much branched, ascending to spreading.
Leaves alternate pinnately divided, 1-3 cm long, oblong, segments entire to deeply few-toothed.
Flowers white, very small, radially symmetrical, petals spatula-shaped, only slightly longer than sepals.
Fruit becoming dry, to 0.3 cm long, a 2-parted, flattened pod, notched at top and bottom, one seed in each inflated, wrinkled segment; styles short, persistent. Inflorescence of loose racemes (spike-like).
Wetland status: UPL.
Frequency in NYC: Very infrequent.
Origin: S. America
Habitat: Open weedy sites.
Note: First observed 2008.