Heracleum maximum
This tall native Apiaceae perennial from North America features large leaves and broad white umbels, self-seeds vigorously, and possesses caustic sap that can cause dermatitis or phytophotodermatitis on skin exposed to sunlight.
Common Names
Cow Parsnip, American Cow-Parsnip, Common Cow Parsnip, American Hogweed, Giant Hogweed, Indian Celery, Indian Rhubarb
Summary
Cow Parsnip is a native North American wetland perennial in the Apiaceae family, typically 4 to 8 feet tall with hollow, stout stems and very large leaves that are palmately divided into three leaflets, it bears large flat topped umbels of small white flowers from May through July, a dramatic feature that attracts a wide range of pollinators, sap contains phototoxic furocoumarins that can cause dermatitis when exposed to sunlight, in cultivation it prefers moist soils and can tolerate full sun to partial shade, thriving in moist habitats such as streambanks and wetlands, it tolerates a range of soils as long as moisture is provided and falls within USDA hardiness zones 3 to 10, propagation is by seed and the plant spreads by seed, making it suitable for native plantings, edge plantings, prairie and butterfly gardens, and erosion control or revegetation projects, it serves as a host plant for swallowtail butterflies and provides nectar for many pollinators, caution is advised when handling sap, as phototoxic compounds can cause skin irritation in sunlight, gloves are recommended.
Lifecycle
Biennial or Perennial
Height
3.5-10 feet
Spread
4-8 inches
Hardiness Zones
Zones 3-10
Sunlight Requirements
Ideally Partial Shade, tolerates Full Sun to Partial Shade, can be grown in Full Sun.
Soil Type
Moist loamy to sandy loam soil with good drainage; tolerant of a wide range of textures (including clay); pH 5.2–7.3.
Soil Drainage
Moist, well-drained soil.
Soil pH
5.4-7.3 pH, moderately acidic to neutral
Bloom Color
White
Bloom Time
Spring and Summer
Foliage Color
Green
Leaf Lifecycle
Deciduous
Growth Rate
Rapid
Seasons of Interest
Spring and Summer
Propagation Methods
Seed propagation (self-seeding), seed viability 3–15 years; no spores, cuttings, division, or layering mentioned
Attracts Wildlife
Attracts bees, butterflies, other pollinators, birds
Taxonomy
- Taxonomic Rank
- Species
- Author
- W.Bartram
- Publication
- Travels Carolina : 344 (1791)
Superior Taxa
- Kingdom
- Plantae
- Subkingdom
- Pteridobiotina
- Phylum
- Angiosperms
- Order
- Apiales
- Family
- Apiaceae
- Genus
- Heracleum
Synonyms
Heracleum douglasii Heracleum inperpastum Heracleum tsurugisanense Sphondylium lanatum Pastinaca lanata Heracleum sphondylium var. lanatum Heracleum sphondylium subsp. lanatum Heracleum sphondylium var. tsurugisanense