Thistle Identification

Asked August 8, 2015, 2:34 PM EDT

Can you help me identify this thistle that grows abundantly in the King County Tolt MacDonald Park? I have photographed the thorny leaf, the arrangement of flowers on the stalk, and the flowers in full bloom. It looks close to cirsium arvense but I found too many differences to be able to classify it with confidence. It has a heady fragrance at this time of year. I would love to plant it on my acreage but not, obviously, if it is a noxious weed. Special thanks for your time and expertise!

King County Washington weeds invasive species canada thistle cirsium arvense

2 Responses

This plant does appear to be cirsium arvense. Note the smooth stems and the leaves that clasp around the stem. It's probably the most common variety of cirsium arvense, var. horridum Wimm. and Grab. (leaves smooth below, thick and wavy, with many marginal spines). The female flowers have a wonderful vanilla-like scent. I'd steer clear of it!

Special thanks, Alice, for your fabulous assistance. This is a superb service to citizens to have authoritative and speedy help.