[1][2][3][4] It is native to western North America, including the southwestern United States to Wyoming and Texas, and into Baja California.

Erythranthe rubellus is an annual herb growing 2 to 32 centimeters tall with a very slender, red stem.

The oppositely arranged oval leaves are up to 3 centimeters long and lance-shaped to oval, the lower ones borne on short petioles.

The herbage is usually lightly hairy and green to reddish in color.

The petite tubular flower is no more than a centimeter long, the base of its tube encapsulated in a narrow, ribbed calyx of sepals.