Erythranthe lewisii aka Lewis's Monkey Flower

Erythranthe lewisii is a perennial in the Phrymaceae family. Its common names include great purple monkey flower and purple monkeyflower. Garden references also list it as Mimulus lewisii. It comes from western North America, from Alaska into the western United States. Its range also includes British Columbia and Alberta in Canada. It grows in temperate regions and is not native to Britain or Ireland.

This plant has an upright form rather than a woody framework. In gardens, it reaches about 0.3–1.6 feet [0.1–0.5 metres] in height. Its spread falls within the same range. The leaves have hairs and feel sticky. Its flowers have two lips and come in shades of pink. These range from rose pink to purple pink. Each flower can reach about 0.16 feet [0.05 metres] long. The flowers appear through summer, giving this small perennial a long season of bloom.

In the wild, it grows beside streams and on wet slopes. It also grows within streams at middle to high elevations. These habitats help explain its need for very moist garden soil. Give it fertile soil with plenty of humus. Full sun and light, dappled shade both suit it. A dry site does not match the growing conditions described by the sources. PFAF lists it for USDA hardiness zones 4–8. Its water needs remain important when choosing a place to grow it.

Its small size suits wet areas where taller plants may dominate. PFAF lists pond settings and bog gardens among its garden uses. It also lists sunny woodland edges and sites with dappled shade. These settings combine its need for moisture with suitable light. Sow seed in spring to raise new plants. Cut the growth back once flowering ends. The RHS reports few routine pest or disease problems. It does not name a pest or disease that needs special control.

PFAF reports that people can eat the leaves and stems. They may eat them raw or cook them first. It gives the plant a modest food-use rating of two out of five. The same source lists no known hazards. That statement does not establish safety for pets. PFAF also records a poultice use, but gives no preparation details. Its medicinal rating is one out of five.