Potentilla erecta aka Tormentil

Potentilla erecta is a small perennial in the rose family. Its common names include tormentil and erect cinquefoil. It comes from Europe, northern Africa, and southwestern Asia. It is native to Britain and Ireland. Wild plants grow in grassland, heath, bogs, and open woods. They also grow on mountain slopes and in fens. Many of these sites have light, acid soil.

The plant forms clumps and spreads through woody rhizomes. Garden plants reach about 1–1.6 feet [0.3–0.5 metres] tall. Flower stalks can reach 2 feet [0.6 metres]. Missouri Botanical Garden gives a spread of 1.5 feet [0.46 metres]. RHS gives a wider range, reaching 3.3 feet [1 metre]. Slender stems stand upright or lie along the ground. Green leaves cluster close to the ground and around stems. Each leaf has three to five glossy leaflets with deep teeth. The leaflets range from lance-shaped to wedge-shaped. Foliage may die back or remain partly green in winter.

Bright yellow flowers rise above the leaves on long stalks. Each flower measures about half an inch across. The flowers have four petals, unusual within the rose family. Missouri Botanical Garden lists flowering from May through August. RHS reports that blooms can last into October. The flowers suit border fronts, rock gardens, and herb gardens. The plant also fits cottage gardens and wildlife planting. RHS warns that people and pets must not eat its fruit.

Grow tormentil in moist soil that drains well. Full sun suits it, though it also accepts part shade. It prefers light loam but grows in sand, clay, and chalk. It tolerates acid, neutral, and alkaline soil. Its water needs are moderate, and routine care is light. It needs no pruning and takes two to five years to mature. Growers can raise it from seed or semi-hardwood cuttings. It is hardy in USDA zones 5–8 and rated H6 in Britain. Pests rarely cause trouble, but honey fungus can attack it. Missouri Botanical Garden also lists resistance to deer.

The roots contain much tannin and yield a red dye. Herbal medicine uses the plant for its astringent action. Rhizomes also provide tea, while long-boiled roots serve as emergency food. These uses do not mean the plant is harmless. Internal use can cause gut symptoms and reduce mineral uptake. PFAF warns against use during pregnancy, breastfeeding, or inflammatory bowel disease.