Oenanthe aquatica aka Fine Leaf Water Dropwort

Oenanthe aquatica is also called fine-leaved water dropwort. It belongs to Apiaceae, the carrot family. Its native range runs from Europe to Mongolia and northern Iran. Britain and Ireland also form part of its native range. This wetland plant grows in regions with a temperate climate. It lives in still or slow water and along streams. It also grows in damp meadows, pond edges and ditches.

This perennial forms clumps and lives for more than two years. It can float or grow on land. Garden plants reach about 3.3–4.9 feet [1–1.5 metres] tall. They spread about 1.6–3.3 feet [0.5–1 metre] wide. Plants take two to five years to reach full size. The small leaves are mid-green, with parts shaped like fans. The RHS lists them as deciduous or partly evergreen. Thus, plants may lose their leaves or keep some. Small white flowers each have five petals. They form compound umbels, with small flower clusters on branching stalks. The flower heads bloom from June through September. This show gives the plant value beside ponds and in bog gardens.

Grow this plant in sun or partial shade. It needs wet ground or water, not a dry border. The RHS lists clay and loam as soils that suit it. It accepts acid, neutral and alkaline soils. Yet Plants For A Future says wild plants avoid acid sites. The RHS advises a spot with shelter. It gives the plant a cold rating of H7. Missouri Botanical Garden lists USDA zones 5–8. These are two systems for rating how much cold plants withstand.

Suggested sites include wet areas and wildlife gardens. Yet its spread can become a nuisance without checks. Bear this risk in mind when choosing pond-edge plants. It needs little routine care and no pruning. Divide plants in late spring to raise more. Serious pests and diseases seldom cause problems. Slugs and snails may still attack it. Missouri Botanical Garden also reports no major insect or disease concerns.

All parts are poisonous, so this is not a food plant. The RHS warns that eating it harms people and dogs. It advises wearing gloves and clothes that protect you when handling plants. Plants For A Future lists no edible uses. It records past uses of the fruit and roots as medicine. These include chest treatments and applying it to piles. These records do not make home treatment safe. Excess fruit doses can cause dizziness, intoxication and narcotic effects. The source limits medicinal use to care under an experienced practitioner.