Rocky Mountain Cowlily
Nuphar polysepala
Last reviewed: June 2026
Light
part shade
Water
high
Size
12"–36" H × 24"–48" W
Bloom
Jun, Jul, Aug
Native to
AZ, CA, CO, ID and 7 more states
Pollinators
beetles, flies
Browse plants for this ecoregion
Rocky Mountain cowlily is an aquatic perennial native to mountain lakes and ponds. It produces large, round floating leaves and bright yellow cup-shaped flowers during summer months. This plant requires standing water or consistently saturated soil to thrive.
In an HOA neighborhood
Rocky Mountain Cowlily takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Requires pond or water feature
- Very specialized growing conditions
- May appear unkempt without proper water management
Wildlife value
The flowers attract beetles and flies for pollination. Seeds and rhizomes provide food for waterfowl and other wetland wildlife.
Common questions
- How much sun does Rocky Mountain Cowlily need?
- Rocky Mountain Cowlily grows best in part shade conditions.
- When does Rocky Mountain Cowlily bloom?
- Rocky Mountain Cowlily blooms in June, July, and August.
- Where is Rocky Mountain Cowlily native?
- Rocky Mountain Cowlily (Nuphar polysepala) is native to AZ, CA, CO, ID and 7 more states, per the USDA PLANTS Database and regional native plant society lists.
- What pollinators does Rocky Mountain Cowlily attract?
- Rocky Mountain Cowlily draws beetles and flies.
- Is Rocky Mountain Cowlily HOA-friendly?
- Rocky Mountain Cowlily takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
Native range data from the USDA PLANTS Database and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Ready to grow Rocky Mountain Cowlily? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Not sure where to start? Take the 2-minute yard quiz