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