Stillingia spinulosa is a species of flowering plant in the euphorb family known by the common name annual toothleaf.

[1] It is native to the Southwestern United States where it occurs in the creosote scrub of the deserts.

It is an annual or perennial herb producing a clump of thick, leafy stems approaching a meter in maximum height.

The inflorescence is a stout spike of flowers 1 to 2 centimeters long.

The ovary of the female flower develops into a three-lobed greenish capsule about half a centimeter wide.