Lithospermum

Lithospermum is a genus of flowering plants in the family Boraginaceae, commonly known as gromwells or lithosperms. The genus includes herbaceous perennials and some shrubs native to temperate regions of Europe, Asia, and North America. Plants are typically low-growing and may have rough, hairy leaves. They produce small flowers arranged in coiled inflorescences (scorpioid cymes), with five-petaled tubular corollas that can be yellow, orange, white, or pale in color. The flowering period usually occurs in spring to summer.

The fruits of Lithospermum are schizocarps that split into two nutlets. The seeds are characteristically hard, which contributes to the common name “stone seeds” and to the genus name Lithospermum (stone seed).

Notable species and uses include Lithospermum officinale (common gromwell), historically used in herbal medicine and as a yellow dye. Lithospermum erythrorhizon (Japanese or Chinese gromwell) is the source of shikonin, a red pigment used in traditional medicine and cosmetics. Lithospermum canescens (hoary puccoon) is native to North America and valued in some regional applications. Ecologically, Lithospermum species contribute to their native plant communities and can be grown in gardens with well-drained soil.

Cautions and chemistry: some Lithospermum plants contain various phytochemicals, and traditional uses exist but may carry risks, particularly if used internally without supervision. As with many Boraginaceae, there is potential for pyrrolizidine alkaloids in some species, so handling and use should be informed by reliable sources.

Cultivation notes: these plants prefer sunny locations with well-drained soil and are relatively drought-tolerant. Propagation is generally by seed or division.