Common monkeyflower blooming along a small spring at Tin Can Springs along Forest Service Road #2860, Malheur National Forest........July 18, 2010.
Common monkey flower is an attractive annual or perennial with many erect or spreading stems from 15-60 cm high. Plants commonly root where the nodes touch the ground. Plants growing in seeps will typically grow higher while those of more arid habitats will be much smaller and less branched. The lower leaves are several veined from the base with ovate to lance-shaped blades which are obtuse to rounded at the tips, with long petioles, and often with ragged lobes towards the base of the blade. The upper leaves are short-petioled or sessile with the blades up to 10 cm long and with toothed margins. The lowest leaves commonly wither quickly while the upper persist. The stem leaves are opposite.
The large, showy flowers are in racemes. The flower stems range up to 6 cm in length. The calyx is ridged with 5 lobes, the uppermost lobe being the longest. The corolla is tubular and much longer than the calyx. The corolla itself is 1-4 cm long. The mouth of the corolla is two-lipped (2 upper lobes and 3 lower) and has many hairs and red spots in the throat. The lower lip is larger than the upper. The calyx is inflated when in fruit.
Common monkey flower inhabits wet places from sea level to moderate elevations in the mountains both in the forests, along roadsides, and well into arid regions.
Common monkey flower is found over much of western North America. It ranges from Alaska and the Yukon south to northern Mexico and east to the Rockies.