Blue oxalis is a prostrate herb, growing up to 10 to 20 cm tall. Its leaves are trifoliate (three-parted, like a clover leaf), with each leaflet being 8 to 20 mm long and similarly wide (exceptionally up to 4 cm). The flowers of P. communis are borne singly or in clusters of up to three flowers on stalks that are typically 8 to 15 cm long, but can be 1.5 to 25 cm long. The flowers are generally blue, but occasionally white or purple. Each pod is 1.5 to 2.5 cm long and 4 to 5 mm wide and contains 8–12 seeds, with each seed being around 2 mm long and slightly kidney-shaped, somewhat narrower than long. The genus blue oxalis has only one species. It is found in the mountains of Asia and tropical Africa, and has been introduced to New Zealand.