Mimulus bigelovii is a species in the Phrymaceae (Lopseed) family known by the common name Bigelow's monkeyflower. It is native to the southwestern United States, where it grows in desert and slope habitat. This is a hairy annual herb producing an erect stem 2 to 25 centimeters tall. The plant is variable in size and shape as well as color, the herbage being green to nearly red in color. The pointed oval or rounded leaves are each up to 3.5 centimeters long and arranged in opposite pairs about the stem. The tubular base of the flower is surrounded by a reddish-green or purple ribbed calyx of hairy sepals with long lobe tips. The trumpet-shaped flower corolla is roughly one to two centimeters long and has a very narrow tube and a wide mouth. The corolla has two upper lobes and three lower, and is generally magenta or deep pink in color with darker red, purple, and yellow spots in the throat. This plant is seldom seen in the garden but is common in desert canyons in spring of good rainfall years.