Euphorbia serpyllifolia is a species of euphorb known by the common name thymeleaf sandmat, or thyme-leafed spurge. It is native to a large part of North America from Canada to Mexico, where it is a common member of the flora in many types of habitat. This is an annual herb growing as a prostrate mat or taking a somewhat erect form. The oblong leaves are up to about 1.5 centimeters long, sometimes hairy and finely toothed along the edges. The tiny inflorescence is a cyathium about a millimeter wide. It bears scalloped white petal-like appendages arranged around the actual flowers. At the center are several male flowers and one female flower, which develops into a lobed, oval fruit up to 2 millimeters wide. This plant had a number of traditional medicinal uses for many native American groups.