Calirhoe involucrata, Winecup

Winecup, Buffalo rose
Calirhoe involucrata

Hardiness: Zones 4 to 9
Plant type: Herbaceous perennial
Height: 6"- 1'
Spread: 6"- 3'
Sun: Full sun 
Water: Dry to medium
Bloom time: May, June
Bloom color: Magenta
Soil: Well-draining, sandy or loamy soils, tolerates clay and poor soils

Notes: Look spectacular spilling over a rock wall or tumbling down a bank.

More information on this plant here.