- Latin synonym: Lithospermum arvense
- Name also: Bastard Alkanet
- Family: Borage Family – Boraginaceae
- Growing form: Annual herb. Taproot strong, brown, source of reddish-violet dye.
- Height: 15–45 cm (6–18 in.). Upper stem sparsely branched, hair growing upwards flush with stem, base reddish.
- Flower: Regular (actinomorphic), 3 mm (0.12 in.) wide. Corolla yellowish white, fused, narrowly funnel-shaped, 5-lobed, hairy. Upper part of calyx-tube bluish. Calyx fused, deeply 5-lobed, lobes narrow, needle-like. Stamens 5. Gynoecium fused, single-styled. Inflorescence a scorpioid cyme, flowers with subtending bracts, subtending bracts resemble stem leaves.
- Leaves: Alternate. Basal leaves stalked, winged, upper stem leaves stalkless. Blade narrowly ovate–lanceolate–oblanceolate, with entire margin, both sides hairy.
- Fruit: 4-parted schizocarp. Mericarps greyish brown, with granular surface, 2–3.5 mm (0.08–0.14 in.) long.
- Habitat: Grain fields, rocky outcrops in villages, waste ground, harbours, loading areas, railway yards.
- Flowering time: June–July.
- Endangerment: Endangered.
Genus Lithospermum contains around 50 species. Its scientific name literally means stone-seed, and there was no need to explain why to anyone who had ever bitten down upon one: the bread that ancient Finns ate often contained corn gromwell’s rock-hard seeds. A purple dye could also be obtained from the root, and women would use this e.g. as rouge. It has a long tradition of being used in this way – at least 20,000 years according to finds. Despite this endearing usage, the species has primarily been a weed in Finland.
Like many other field weeds, corn gromwell is a follower of rye. Nowadays it is much rarer than it used to be and has almost disappeared in many areas, mainly due to changes in methods of agriculture. Its decline began with the development of land-use methods and more efficient seed-cleaning. Mechanical ploughs, field fertilization and weedkillers made sure of its disappearance. Like many other field weeds it is probably native to the steppes of south-eastern Europe, although this is only an educated guess. It spread all over Europe with the grain trade and reached Finland in the Middle Ages at the latest. It still clings on tenaciously on rocky outcrops and beside roads in south-western Finland.
In Finland rarer than corn gromwell is common gromwell (name also European stoneseed), which occasionally grows in southern Finland. It can be recognized by its narrowly ovate and clearly veined leaves and smooth fruits (schizocarps).