Cow Parsnip vs Showy Milkweed - TreeTime.ca

Cow Parsnip vs Showy Milkweed

Heracleum maximum

Asclepias speciosa

CUSTOM GROW

NOT AVAILABLE THIS SEASON - MIGHT RETURN

Cow Parsnip
Showy Milkweed

Cow Parsnip is a native perennial wildflower known for its tall growth, very large leaves, and broad clusters of white flowers. The abundant blossoms provide nectar and pollen for a wide variety of pollinators, including bees and butterflies. Birds and small mammals feed on its seeds, while the foliage serves as a larval host for certain butterfly species.

Cow Parsnip is often among the first native perennials to establish in disturbed or open sites. It typically grows in moist meadows, along streambanks, forest edges, and roadsides. Although usually a short-lived perennial or biennial, it readily self-seeds and maintains strong populations where conditions are favorable.

Cow Parsnip is the only native Heracleum in North America and should not be confused with the highly invasive Giant Hogweed (H. mantegazzianum).

Note: The sap of the Cow Parsnip can cause phytodermatitis when exposed to ultraviolet light (sunlight). This can cause rashes or even burns. Care should be taken if pruning or handling this plant.

Showy Milkweed is a native perennial wildflower known for its fragrant clusters of pink to purple, star-shaped flowers. It is an essential plant for Monarch butterflies, acting as a critical host plant for caterpillars and a nectar source for adults. Blooming from early to mid-summer, these flowers also supply nectar to many other pollinators, including bees, butterflies, moths, and hummingbirds.

Ideal for butterfly conservation, pollinator gardens, and naturalization projects, Showy Milkweed thrives in a wide range of soils, including dry and rocky ground. While it spreads via underground rhizomes to form colonies, it is much less aggressive than Common Milkweed (Asclepias syriaca).

Note: All parts of the plant contain toxic cardiac glycosides, especially the milky sap. Do not ingest any part of the plant and prevent sap from contacting skin or eyes. Toxic to humans, pets, and livestock.

Cow Parsnip Quick Facts

Showy Milkweed Quick Facts

Zone: 2a
Zone: 3a
Height: 1.8 m (6 ft)
Height: 0.9 m (3 ft)
Spread: 1.2 m (4 ft)
Spread: 0.5 m (1.5 ft)
Light: partial shade, full sun
Light: full sun
Moisture: normal, wet
Moisture: dry, normal
Growth rate: fast
Growth rate: fast
Life span: short
Life span: short
Growth form: upright
Growth form: upright, clump forming
Spreading: seeds - low
Spreading: rhizomes - high, seeds - high
Maintenance: medium

Toxicity: sap causes skin irritation

Toxicity: toxic to pets, livestock, and humans if ingested, can cause skin and eye irritation.
Foliage: very large, palmate leaves
Flowers: large clusters of white flowers
Flowers: purplish-pink clusters
Bloom time: spring to early summer
Bloom time: early to mid summer
Hybrid: no
Hybrid: no
Catkins: no
Catkins: no


Native to: AB, BC, SK, MB, ON, QC, NS, NB, NL, YT, NT, PE
Native to: AB, BC, MB, YT
Other Names: american cow parsnip, common cow parsnip