06/11/2026
Before you pull that thistle, take a second look. You might be removing a pollinator powerhouse by mistake.
Not all thistles are bad! Our native field thistle (Cirsium discolor) provides important resources for pollinators and other wildlife, while invasive Canada thistle (Cirsium arvense) spreads aggressively and can quickly take over fields, roadsides, and natural areas.
One of the easiest ways to tell them apart is by looking at the leaves and bracts. Bracts are the small leaf-like structures located just beneath the flower head. Field thistle has bright white leaf undersides, deeply lobed leaves, and green bracts. Canada thistle has green leaf undersides, more shallowly lobed leaves, and bracts with a noticeable purple tint.
Learning the difference helps solve a common problem for landowners and gardeners: controlling invasive plants without accidentally removing beneficial native species.
Have you ever mistaken a native plant for an invasive one? Let us know in the comments!
Learn more about invasive and native species at sicim.info