Polanisia dodecandra (L.) DC.
Family: Cleomaceae
rough-seed clammy-weed
Polanisia dodecandra image
from USDA Plants website  
Etymology: Polanisia: from poly for "many" and ansos for "unequal," referring to how this differs from the stamens in Cleome
Plants: erect, annual, 8"-20" tall forb, with sticky hairs and unpleasant odor
Leaves: 3-parted, on stalks about the same length as the leaf blade
Flowers: white to pinkish, 4-parted, 1/4" long, irregular-shaped with long claws, the side petals longest, stamens much longer than the petals; inflorescence a terminal cluster (raceme) of many, stalked flowers; blooms July-Sept.
Fruits: long, pea-like capsule, mostly stalkless, erect, slightly hairy, sticky
Habitat: disturbed sites, stream sides; in gravelly, sandy soil
Conservation Status: Native
Characteristic of sandy or gravelly places, especially bars, flats, islands, and banks along major rivers and barrens, dunes, and sand and gravel pits on associated terraces, also on gravelly or cindery railroad ballast, less often on roadsides, vacant lots, and waste ground, rarely on sandstone bluffs and Lake Michigan beaches.

Most Wisconsin collections belong to subsp. dodecandra, having relatively small flowers [largest petals 3.5–6.5 (–8) mm long] and fruits (2–5 cm long). The western subsp. trachysperma (Torr. & A. Gray) Iltis has the largest petals (7–) 8–13 (–16) mm long and fruits 3–8 cm long. It is unquestionably represented by one collection, probably adventive, from Arena (H. H. Iltis s.n. in 1957, WIS). The two taxa are part of a morphological continuum (Iltis 1958), and three Wisconsin collections have been annotated by Iltis as intermediates.