American Sweet Flag vs Cow Parsnip

American Sweet Flag is a native perennial wetland plant found along shorelines, streams, wet meadows, and marshes. Its extensive rhizome system allows it to spread and stabilise soil, helping maintain the edges of ponds and streams. This dense growth provides cover for small animals and supports overall wetland biodiversity, while the rhizomes and seeds serve as food for small mammals and waterfowl. Cold-hardy and resilient, it is well-suited for ecological restoration, riparian plantings, erosion control, and naturalization projects.

The plant grows in dense clumps with tall, sword-shaped leaves that release a citrus-like scent when bruised. The rhizomes are aromatic, with a spicy, cinnamon-like fragrance that has been used in perfumery and flavouring. In early summer, American Sweet Flag produces a distinctive floral spike (spadix), adding visual interest to wetland plantings.

Cow Parsnip is a native perennial plant that grows tall with very large leaves and broad clusters of white flowers. It grows quickly, providing quick cover in disturbed areas.
Its flowers are large and plentiful, providing nectar and pollen for bees, flies, and butterflies. Its seeds are eaten by birds and small mammals. The young shoots of the plant are edible, but care must be taken as the sap of this plant can cause skin irritation (see below).
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.

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