Wanted: Dead or not alive

There are several non-native thistles that have been spreading in Texas for a number of years. Most thistles you will see on the grasslands are native. They are great plants that are used by many pollinators. I have previous shown you the Painted Lady butterflies that uses our native thistles for a host plant. Good thistle!

Musk Thistle (Carduus nutans), Scotch Thistle (Onopordum acanthium), and Milk Thistle (Silybum marianum) are the bad ones or non-native. I have seen all three of these non-native thistles in North Texas and of course other parts of Texas as well. Additionally, I have run across all three in Wise County.

First up is the Musk Thistle in the foreground. Bad! The one in the back is the native Texas Thistle, good one!
The phyllaries (the part directly under the flower) are much wider and spread.
Here is the whole plant. Look at the spiny leaves that are decurrent on the stem. This one was on the grasslands. The Musk Thistle is native to western and central Europe, northwards to Scotland and extending to Sicilia, central Yugoslavia, and Ukraine , western Siberia, Asia Minor, and North Africa. It is a pretty plant and our pollinators will use it. However it can spread rapidly by dispersal of hundreds of seeds. Certainly it is advisable to remove it quickly!
At the request of the Forest Service we bagged them to so as not to let them spread. So on the first afternoon we bagged only part of them. However I cut off the heads of those that had already gone to seed to prevent their spreading more until we could get back the next day to finish the job.
Jim and I removed six bags from the unit near us. And let me tell you the ground is hard and dry.
Oh no, the Scotch Thistle was found as we were leaving the unit. Bad thistle!

Its thin phyllaries spread and the spines go all the way to the inflorescence. There were only a half dozen small ones. I had not seen this on the grasslands for some years. Well, hopefully that would be it.
Oh NO! MORE on the other side of the unit! This afternoon I had decided to go scouting further. Gosh I am glad I did. These were well over seven feet tall! Furthermore, luckily there were not many. I might need a chain saw…just kidding. Sorta. πŸ˜‰ However I was not equipped to get them today. So I certainly, I will dispatch them very soon.
An American Lady did stop in for a sip on the non-native thistle.
The third non-native thistle is the Milk Thistle. This photo was taken at Lake Ray Roberts State Park in 2010.
You can see the phyllaries spread at a right angles.
The leaves are white veined. Bad thistle for us. It is a fine plant in its native habitat in the Mediterranean, Europe, Central Asia, India, Ethiopia and possibly near the coast of southeast England.

So I actually do not hold a grudge against the above thistles. They are just trying to survive. And they certainly are really pretty. Furthermore, they are great plants in their native lands. In fact to be fair many of our North America plants have become invasive in other parts of the world.

In summary, our native thistle species are important to our plant diversity. Furthermore, the non-native thistles can quickly overwhelm a habitat. So I hoped this helps you identity the non-native thistles.

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Keep looking!

The more you know, the more you see and the more you see, the more you know.


  1. Thistles. Ugh! They may be pretty but not when you run into oneπŸ˜„. Job well done Mary. Thank you.

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