Mimulus glaucescens is a species of monkeyflower known by the common name shieldbract monkeyflower. It is endemic to California, where it is known only from the foothills of the southernmost Cascade Range and adjacent northernmost Sierra Nevada. It grows in moist areas, such as seeps. It is endemic to California, where it is known only from the foothills of the southernmost Cascade Range and adjacent northernmost Sierra Nevada. It grows in moist areas, such as seeps. Mimulus glaucescens is an annual herb varying in maximum height from 6 to 80 centimeters. The stem is hairless and waxy. The oval to rounded leaves are up to 7 centimeters long and are sometimes borne on petioles. The inflorescence is a raceme of flowers with a distinctive pair of bracts completely fused around the stem to form a rounded disc up to 4. 5 centimeters wide. The flowers are up to 3. 5 centimeters long, spreading at the mouth into an upper lip with two notched lobes and a lower lip with three. The flower often has red spotting in the mouth.