Oxalis purpurea is one of the most commonly cultivated ornamental species of the genus. In our garden it dies back to the ground in summer and returns with cooler weather. The leaves of the ‘Garnet’ are a rich purple with pink flowers and while it is somewhat invasive, not as much as the green leaved one with pink flowers.  The color matches nicely with the Japanese Maple, "Crimson Queen" and Persicaria in the above photo.