Flower:

The ½-inch bright yellow flowers are highly irregular with two upper lobes and three lower, and emerge from upper leaf axils on short stems.The lower lip is hairy (bearded) into the throat with two reddish-brown spots at the base. The calyx cupping the flower is bell-shaped, up to ½ inch long, with 5 unequal lobes.

Leaves and stem:

Leaves are smooth to slightly hairy on upper leaf surface. The leaves are opposite and generally round with smooth to slightly toothed edges, are ¼ to 1 inch in diameter with lower ones on short stems while upper leaves clasp the stem. Stems are smooth to sparsely hairy, diffusely branched and often very red.

Fruit:

Fruit is a 2-celled capsule wrapped in the persistent calyx, which turns papery as fruit matures.

Inside are numerous oval, golden brown seeds each about .5 mm long.

Notes:

The stems of Round-leaf Monkey Flower are weak so it tends to grow prostrate but may be ascending, sometimes just at the tips. While not as commonly encountered as the blue Allegheny Monkey Flower (Mimulus ringens), this smaller yellow flowered species ranges from almost the arctic circle to S. America. There are 4 varieties of S. glabratus in North America, though they are not well-documented; var. jamesii, formerly var. fremontii, is the most common and is present in Minnesota.