It is native the west coast of the United States from Washington to California, where it grows in moist areas at low elevations.

Alopecurus saccatus is an annual bunchgrass, forming tufts of stout, erect stems up to about 45 centimeters in maximum height.

The inflorescence is a dense panicle up to 6 or 7 centimeters long which blooms in yellow to reddish brown anthers.

The spikelets are between 3 and 5 millimeters long, with a bent and exceeding anthers.

The glumes are between 3 and 5 millimeters long, fused at the base, and the tips are obtuse.