Annual or biennial herb 10 - 30 cm tall Stem: upright to spreading, mostly unbranched. Flowers: in a loose, branched cluster, stalked, white, 1 - 4 mm long. Sepals four, green. Petals four, longer than sepals. Stamens six. Fruit: a narrow pod, upright on an ascending stalk, 2 - 3 cm long. Basal leaves: few or none at flowering, pinnately divided, stalked. Terminal leaflet oblong to broadly triangular. Stem leaves: four to ten or more, alternate, stalked, mainly 2 - 4 cm long, pinnately divided into long, thin, similar leaflets (3 - 6 pairs). Terminal leaflet 1 - 3 mm wide, linear to triangular-oblong, sometimes toothed. Lateral leaflets not much smaller (1 - 3 mm wide), linear to linear- spatula-shaped or narrowly oblong.
Similar species: The similar Cardamine pensylvanica is larger and grows in wet habitats. Also, its terminal leaflet is broader than the lateral leaflets, and the leaflet bases extend down along the leaf axis. The stem leaves of C. hirsuta differ by having a marginal fringe of hairs at the base of their leafstalks.
Flowering: mid-April to early July
Habitat and ecology: A plant typically found in the dry soil of lawns, fields, and open woods; in both shade and sunlight. In the Chicago Region, it has been found growing in ditches, fallow fields (often cornfields), and poorly drained old fields. In a dolomite prairie they were seen occupying the areas containing bare soil and exposed rock.
Occurence in the Chicago region: native
Etymology: Cardamine comes from the Greek word kardamon, which refers to plants in the cress family. Parviflora is Latin for "small flower." Arenicola means "growing in sandy places."