Myosurus apetalus is a species of flowering plant in the family Ranunculaceae known by the common name bristly mousetail.

It grows in moist and wet habitat, such as marshes, meadows, and vernal pools.

It is an annual plant forming a small tuft up to about 12 centimeters tall.

The leaves are linear and narrow, sometimes threadlike, and reach up to 6 centimeters in length.

The inflorescence produces a single flower which has an elongated, cylindrical or cone-shaped receptacle up to 1.5 centimeters long.