Verbena officinalis aka Vervain

Verbena officinalis is a perennial wildflower known as common vervain. It belongs to the verbena family, Verbenaceae. Its native range spans the Old World and reaches Australia. It is native to Britain and Ireland as well. Plants grow on roadsides and waste ground, away from shade. Human activity has helped it spread far beyond its native range. It now grows in both temperate and tropical regions.

The plant grows upright, with branches and a narrow outline. Garden plants reach about 1.6–3.3 feet [0.5–1 metre] tall. The RHS description gives 2.3 feet [0.7 metre] as its height. Its spread is about 0.3–1.6 feet [0.1–0.5 metre]. The leaves have deep lobes and a rough, hairy surface. The plant loses its leaves during the dormant season. Thin flower spikes rise above the leaves in late summer. They carry many small flowers in a pale purple shade.

Grow vervain in full sun, in soil that drains well. It suits poor soil or soil with modest fertility. Neutral to alkaline soil suits it better than acid ground. Chalk, loam and sand all appear in the RHS soil guidance. Soil can hold moisture, but it must let excess water drain. The RHS rates its UK hardiness as H5. Plants For A Future lists USDA zones 4–8. Plants reach their mature size within one to two years. Growers can raise new plants from seed or divide existing plants.

Vervain fits cottage gardens, meadow beds and loose prairie-style planting. It also has a place in gardens grown for wildlife. Bees, flies, butterflies and moths help pollinate its flowers. Plants can also pollinate themselves and set seed without another plant. They can seed freely where conditions suit them. Sources differ on whether to class this as weed potential. Established plants can cope with neglect and nearby weeds. They need no pruning, and pests and diseases rarely cause trouble.

Both leaves and flowers have recorded food uses. People boil the leaves briefly before seasoning and eating them. Leaves also serve as a tea ingredient; flowers serve as garnish. Vervain has a history of use in herbal medicine. These uses do not mean all doses are safe. Plants For A Future warns that high doses can cause convulsions. It also warns of effects on blood-pressure medicines. Avoid medicinal use during pregnancy or while breastfeeding.