Lithospermum is a genus of plants belonging to the family Boraginaceae. The genus is distributed nearly worldwide, but most are native to the Americas and the center of diversity is in the southwestern United States and Mexico. Species are known generally as gromwells or stoneseeds.

Taxonomy

Plants of the World Online currently accepts 84 species. Other sources accept about 50 to 60 species in the genus. A 2009 molecular study showed that the genus Onosmodium is included within Lithospermum.

Species

84 species are accepted.

Formerly placed here

Ecology

Lithospermum leaves are eaten by the caterpillars of certain Lepidoptera, such as the moth Ethmia pusiella which has been recorded on L. officinale.

Uses

The dried root of Lithospermum erythrorhizon is a Chinese herbal medicine with various antiviral and biological activities, including inhibition of human immunodeficiency virus type 1 (HIV-1). Lithospermum erythrorhizon is native to Japan, where it has been traditionally used to make a purple dye. In southwestern North America, a species of this genus was used as a contraceptive by the Shoshone Native American tribe.

Fossil record

7 petrified nutlets and nutlet fragments of a Lithospermum species have been described from the Late Miocene Ash Hollow Formation, Ogallala Group, five km south of Martin in Bennett County, South Dakota. †Lithospermum dakotense sp. nov. shows similarities in size, shape, attachment and epidermal cell patterns to extant Lithospermum species. The fossil nutlets were preserved in various stages of maturity. The fossils closely resemble the nutlets of Lithospermum caroliniense and Lithospermum incisum.