Cardamine oligosperma has a distribution that spans much of western North America; the occurrence span British Columbia to California and extends eastward to Montana and Colorado. Elevations of occurrence are generally less than 1100 meters. Preferred habitats are shady canyons, riparian zones and stream bottomland.

With a common name of Little western bittercress, this species may present as an annual or biennial. The growth form is taprooted with stems erect to ascending. The plant height is usually greater than 20 centimeters and typically in a branched form. There are numerous leaves arranged in a a basal generally rosetted architecture. The leaves are 1-pinnate, with five to nine lateral leaflets. Inflorescences are elongated and three to ten centimeters long. Flowers have white petals that are two to four millimeters long. Fruits are ascending to erect, and 15 to 25 mm long. Seeds are oblong-ovate, narrowly margined. Chromosomes: 2n=16

Cardamine oligosperma Nutt.:
United States (North America)

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Isotype for Cardamine unijuga Rydb.
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): J. Flodman
Year Collected: 1896
Locality: Spanish Basin, Madison Range., Montana, United States, North America
Elevation (m): 1829 to 1829

Rounded Global Status Rank: G5 - Secure

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: T5 - Secure

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N4 - Apparently Secure

Comments: Lihova et al. (2006) recognize Cardamine oligosperma in the strict sense, not including C. oligosperma var. kamtschatica.