Spreading groundsmoke is a simple to freely branched annual from 10-50 cm high. In well-developed individuals, no central stem may be seen. The herbage is often glabrous but may range to thinly covered with appressed to spreading hairs. The leaves are all found on the stems and are reduced in size upwards on the stems. They are linear in shape and up to 6 cm long and 5 mm wide.
The flowers are either small and inconspicuous to fairly showy. The smaller flowers are adapted for self-pollination while the larger flowers are adapted for cross-pollination. The 4 sepals are each 1-5 mm long and are reflexed in pairs when in bloom. The 4 petals are each 1.5-6 mm long and white in color with a yellow spot near the base, the petals becoming rose-color with age. The stamens range from 0.9-6 mm long and with the style are roughly equal to the petals. The stigma is hemispheric to subglobose in shape. The fruit is a capsule from 5-15 mm long and about 1 mm wide. It is cylindrical with the covering slightly constricted between the seeds. The capsules are spreading to reflexed downwards.
var. diffusum:
var. parviflora:
Spreading groundsmoke may be found in moderately moist to dry ground on open to lightly wooded sites , both on flat ground as well as on slopes. It is often found in association with sagebrush and is sometimes found in disturbed soils, including those along roadsides. It may be found to elevations of 3175 meters.
Spreading groundsmoke may be found from southern British Columbia south through the Pacific Northwest to northern Baja California and east to Montana, western South Dakota and south to Arizona and New Mexico.