Canada Thistle
Cirsium arvenseAsteraceae — Aster family
Invasive non-native

White Clay Creek State Park -- Possum Hill
June 2001

Prides Crossing
September 2009

White Clay Creek State Park -- Possum Hill
June 2011

White Clay Creek State Park -- Possum Hill
May 2020
Guide to Cirsium of Delaware
Search Google • Delaware • USDA
Photos copyright David G. Smith
Information from the Delaware Flora Checklist used with author's permission.