Nuphar pumila aka Least Water Lily

Nuphar pumila is a perennial water plant in the waterlily family, Nymphaeaceae. Its common names include least waterlily and yellow pond-lily. It grows from a rhizome and lives in water. Its native range spans subarctic and temperate parts of Eurasia. This includes northern Europe, Siberia, China, Mongolia and Japan. The RHS also lists it as native to Britain and Ireland.

In the wild, it grows in cool ponds and lakes. These waters often have few nutrients and an acid pH. Moorland and mountain lakes form part of its habitat. PFAF records it in lakes in northern Scotland. It can cope with very poor, acid water. This makes its wild habitat more specific than a general pond setting. Still water suits it best, though it also tolerates a slow current.

For cultivation, give it sun or light shade. PFAF recommends water at least 1 foot [0.3 metres] deep. It accepts sandy, loamy and clay soils beneath the water. Its pH range includes mildly acid, neutral and mildly alkaline conditions. It can also grow in very acid conditions. A pond provides a suitable garden setting for this aquatic perennial. The supplied sources give no species-level mature height or spread. They also give no hardiness zone or detailed leaf description.

Flowers appear from July to August. Each flower has both male and female organs. Flies and beetles carry pollen between the flowers. Growers can raise new plants from seed or divide established plants. PFAF places division in May, with one bud on each piece. Keep new divisions in shallow water until they establish. Sow ripe seed in submerged pots in a greenhouse. Move seedlings into separate pots once their first true leaf appears. PFAF recommends growing them under glass for at least two years.

PFAF records the seeds as edible and gives a moderate edibility rating. Its fuller food account borrows possible uses from a related species. Those borrowed uses do not establish how to prepare this plant. PFAF also records a traditional root use as a digestive tonic. That record does not prove medical benefit. It lists no known hazards and no other uses. This does not establish safety for every person or pet. The supplied evidence names no pests or diseases.