- Annual herb, loosely glandular-pilose, the stems erect or decumbent, 0.5-2 dm. tall. Leaf-blades widely ovate, acute, sharply dentate, palmately 3-veined, 1.5-3 cm. long, truncately rounded to petioles rather shorter than blades, the uppermost narrowed and sessile; pedicels becoming 15-60 mm. long; calyx 7-10 mm. long, purple-spotted and -mottled, strongly pilcate-angled, its lobes acute, lowest pair upcurved even to 90 degrees against the longest uppermost one which is 1.5 mm. long; corolla 8-15 mm. long, yellow, the throat nearly cylindric, ventrally with 2 finely pubescent ridges, lower lip with deflexed-spreading lobes, upper lip shorter and ascending; anthers glabrous; capsule stipitate within the inflated calyx, 3.5 mm. long, not dehiscing through septum-apex.
Reference: Abrams and Furris
- This species was recognised by Pennell (1950) but has been reduced to synonymy by most other authors. It is a serpentine endemic restricted to ultramaphic substrates in the mid Sierra Nevada, California. It has narrower leaves than M. guttatus. It is a highly branched, small annual species, believed to be self-fertilising. It does not form cleistogamous flowers.