American Cow-parsnip
Heracleum maximum
Last reviewed: June 2026
American Cow-parsnip is toxic to dogs and cats.
Listed as toxic by the ASPCA Animal Poison Control Center (last reviewed 2026-05-21). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435and your veterinarian's emergency line.
Pollinator Patch flags toxic plants so you can choose a pet-safe native alternative for your yard.
Light
part sun
Water
medium
Size
36"–96" H × 24"–48" W
Bloom
Jun, Jul
Native to
AZ, CA, CO, CT and 36 more states
Pollinators
bees, beetles, flies
Browse plants for this ecoregion
American cow-parsnip is a large, dramatic native perennial that can reach 8 feet tall with massive umbrella-shaped white flower clusters in summer. This bold architectural plant has huge compound leaves and creates a striking focal point in the landscape. It prefers partial sun and consistent moisture to reach its full impressive size.
In an HOA neighborhood
American Cow-parsnip takes more care to keep looking intentional in a front yard. Maintenance level: moderate. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Extremely large size may appear uncontrolled
- Can look messy when stems die back
- May be confused with invasive giant hogweed
Wildlife value
The large white flower umbels attract diverse pollinators including native bees, beetles, and flies during its June-July bloom period. Its substantial size and abundant nectar make it particularly valuable for supporting pollinator populations.
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.
Pollinator Patch flags toxic plants like American Cow-parsnip and shows pet-safe natives for your ecoregion instead.