Description
Arctium tomentosum | Woolly Burdock
Woolly Burdock, also known as Downy Burdock is a biennial herb that was introduced to North America from Eurasia. It is less common than its cousins Common Burdock (Arctium minus) and Great Burdock (Arctium lappa), however is likely found in more areas than records indicate. Plants can be found growing in open fields, along trails, roadsides, and in disturbed soils. A robust and adaptable plant, burdock does well in any light and most soil types, although it does prefer a nitrogen rich environment and some shade.
Arctium tomentosum are towering plants that can reach 5 to 7 feet in height at maturity! As biennials, they send up a basal rosette of large leaves in the first year and typically flower during the second year. Leaves are triangular to heart-shaped with wavy edges, and hairy undersides. The leaves are huge and get smaller as they go up the flower stalk, but the basal leaves can reach lengths of 3 to 4 feet.
In mid-summer, Woolly Burdock grows clusters of large, purple flowers that emerge from bristly bracts, which resemble a thistle. The most distinctive characteristic about Burdock plants are its tiny hooked hairs or burrs that often stick to animals and people upon contact, helping to spread its seed. The most distinctive characteristic about Downy Burdock is that the bristly bracts are densely covered in hairs that resemble a cobweb on the flower heads. The other two Burdocks don’t have this trait, or it’s rare if they do. In any case, the others lack the glandular hairs that are present on Woolly Burdock. Common Burdock is further distinguished by the flowers being mostly very short-stalked, arranged in tight clusters, and Great Burdock by its large flower heads, which are well over 1 inch diameter. Another characteristic to check is whether the lower leaf stalks are solid or hollow. A. minus and A. lappa have solid stalks, and A. tomentosum can have hollow or solid stalks.
Seeds germinate easily with heat, humidity, and light.
Type: Biennial
Sun exposure: Full sun to part shade
Height: 5-7 ft
Mature width- 3-4 ft
Hardiness zones: 3-10
Check out this cool video on Burdock by The Herbal Jedi