- This species is restricted to two small copper mines in Calaveras County, California. It is highly branched and obligately annual. It is self-fertilising, but not cleistogamous. It has reduced corolla spots, and its corolla lobes are pointed. M. cupriphilus lack anthocyanins (red) in the stems. However, hybrids between M. guttatus and M. cupriphilus do have red stems.