Florion Friendly Yards and Neighborhoods: Purple Thistle

Purple Thistle – Cirsium horridulum

I have finally found it! I have met my match! Purple Thistle is a very interesting and beautiful plant that I have absolutely no interest in growing. Its genus is Cirsium which is a name from the greek relative to our Thistle. Stearn’s Dictionary of Plant Names says that this “genus has a great many pernicious weeds and very few plants of value to the gardener.” Also, its species horridulum means very prickly. Step too closely or kneel in the wrong place and you will find out why this species of Thistle was given the name “horridulum.”

C. horridulum is one of 7 species of Cirsium in Florida. Only one of those is not native but all of them are not nice. All have one form or another of a spiny lance like leaf that will be noticed if you are weeding without gloves. The species horridulum is the nastiest though. It’s upright herbaceous stem is formed by alternate spiny leaves that wrap around each other at the base of the plant. It’s leaves are longest and densest at the base of the plant where it forms a spiny rosette. This plant can be from 1 – 5 feet tall and its large head of disk flowers can range from red to pink to purple to white having one – several flowers heads per plant. It can be found growing in ditches, on roadsides, in fields, and in disturbed areas. You may also notice Blue Eyed Grass (S. angustifolium) growing in the same ditches I took most of the pictures.

Its flower is seems to bloom out of a very harsh environment yet it has an almost soft appearance. Its seed is born out of the middle of the flower head waiting for the wind to take it away. I will not be collecting seed of this plant. However, if one randomly comes up in my yard and is not in a hazardous place I will not show to the blade of my hoe but the lens of my camera. This plant is extremely hazardous to humans but not to butterflies. It is an attractant to Sulfer, Swallowtail, and Skipper butterflies and also a host plant for the Metalmark caterpillars who feed on it’s leaves.