Euphrasia officinalis aka Eyebright

Euphrasia officinalis, or eyebright, is a small annual plant. It belongs to the Orobanchaceae family and grows in temperate regions. Kew gives its native range as Finland to western Siberia and Türkiye. The RHS also lists Britain and Ireland as native sites. Plants For A Future places it across much of Europe. That source says botanists disagree on the species' limits. Some see it as a group of closely related species.

Eyebright grows about 0.66 feet (0.2 metres) tall. It spreads about 0.33 feet (0.1 metres) wide. It is a hemiparasite: it draws some resources from other plants' roots. Grasses, red clover and plantains can serve as hosts. Plants For A Future reports little harm to host grasses. It says eyebright enters their roots only a short way. Its short life also helps explain this lack of harm. This root link matters when you choose where to grow it. The source lists lawns and meadows as suitable garden sites.

It blooms from July to September. Each flower has both male and female organs. Bees pollinate the flowers. The plant is also self-fertile. In the wild, it grows in moist grassland and pastures over chalk. It grows in sun or light shade and prefers moist soil. It accepts sand, loam and clay but prefers chalk or limestone. It tolerates mildly acid soil too. Neutral and strongly alkaline ground also suit it. Plants For A Future gives its hardiness as USDA zones 5–9.

To grow new plants, sow seeds where they will grow. Plants For A Future advises sowing among grass in early spring. Keep the site moist, but avoid marshy ground. Its need for host roots makes this more than a soil choice. The evidence gives no specific advice on pests or disease. Plants For A Future does not flag it as weedy. Its small size suits the lawns and meadows that source lists.

The leaves taste slightly bitter. Plants For A Future notes their occasional use raw in salads. People have also used eyebright as an herb for eye complaints. This past use does not prove that eye treatments are safe. The same source warns against its use for eye conditions. It reports red eyes, swelling and pressure after use as a lotion. Other reported effects include headache, confusion, nausea and trouble breathing. These warnings set limits on how to view its past use as medicine.