This species was described by Greene, but has not been subsequently recognised. It appears to be restricted to a small area of Calaveras County, California. It is obligately annual and appears to be self-fertilising. We found it growing on the basalt and conglomerate at the top of Table Mountain, Calaveras Co, in a situation M. guttatus would be unable to grow.
Note by J. Modliszewski (10/24/11) This is not a species! The taxa is described in Greene (1895) as having a large red blotch on the lower middle corolla lobe - consistent with it being a hybrid between M. guttatus and M. nasutus.