Another Example of the Value of Thistles

Thistles are among the most disliked plants in the world. Sure, they’re spiny, and some species have become invasive after being transported outside their native range. But thistle flowers are gorgeous, provide incredible resources for pollinators, and their seeds are nutritious wildlife food. American goldfinches even nest a little later than many other songbirds just (apparently) so they can feed thistle seeds to their kids.

Two painted lady butterflies compete with a digger bee for the bounty found in a native tall thistle (Cirsium altissimum) flower.

So why do people hate thistles so much? Don’t tell me it’s because they’re spiny. The thorns of roses don’t seem to have hurt their popularity. In my neck of the prairie, a lot of people dislike our native thistles because they assume all thistles are invasive, or at least weeds. But even when they learn that species like Flodman’s or wavy-leaf thistles (Cirsium flodmanii and C. undulatum) are native, most people aren’t impressed.

A few years ago, I tried to get some momentum behind the idea that thistles are important for pollinators. That movement didn’t get far, despite it’s catchy (I thought) slogan. I still try to convince people they should be more open minded about thistles, but I don’t really have much hope of success. Despite that, I’m going to present one more piece of evidence on the side of thistle value. Stick with me – the story doesn’t start with thistles but I promise it’ll get there.

This past weekend, I spent two afternoons cutting eastern redcedar trees out of our prairie. For the most part, we catch and cut those trees while they’re still small enough to nip off with loppers. This weekend, though, I was working on the ones that had flown under the radar long enough to grow bigger than loppers can handle. As a result, I was using my noisy chainsaw to knock them down.

As I worked, I started noticing big clumps of grass and other material – mouse nests – embedded in the branches of a few trees. Some were at the bases of the small trees and others were a few feet up the trunk. All were empty, and it took me longer than it should to realize that they were probably vacant only because my noisy saw was scaring the inhabitants off before I got close. I felt bad about disturbing the nests but also really needed those trees to die before they started producing seeds and swarming over the whole prairie. I tried to keep the nests intact as I laid the trees down, hoping the little critters would move back in once I left.

As I neared one particular draw, I started finding a higher percentage of trees with nests in them, and the composition changed from mostly grass to mostly white fluff. Looking more closely, it was clear the fluff was from thistle seeds. I’m pretty sure most of the seeds came from a patch of bull thistles (Cirsium vulgare) I’ve been keeping track of. (Bull thistle doesn’t tend to be very invasive in our area, despite being non-native, so I’m pretty tolerant and just monitor them to make sure they aren’t going crazy.)

A mouse nest built from thistle seeds about three feet off the ground in a small eastern redcedar trees.

I don’t know if the higher abundance of nests in that area was due to the availability of thistle seeds – or even if they really were more abundant versus just being more visible because of their pale color. Regardless, they looked extremely cozy; the insulating value of thistle fluff has to be pretty incredible. Some of the nests were nearly the size of volleyballs and pretty hard to miss, even when obscured by branches full of dark green needles.

So, add one more attribute in the positive column for thistles – they provide great insulating material for winter shelters of mice. And don’t tell me you’re anti mouse and try to spoil my argument. Even if you don’t think mice are cute little critters, which they objectively are, the prairie ecosystem would fall apart without them. Among other things, they’re key food sources for many larger animals and important consumers/transporters of seeds.

Speaking of transporting seeds, the biggest mental image that sticks with me from seeing all those thistle seed nests is not the volleyball-sized masses of fluff. Instead, I’ve been obsessively thinking about those poor mice hauling all that fluff several feet up into those trees. First of all, that’s a tremendous amount of work – gathering the seeds from the tops of spiny plants, hauling it down the plants, across the prairie, and up into the trees. Over and over.

But they’re not carrying those seeds in their paws… they’ve got to be carrying them in their mouths! Imagine stuffing your mouth full of thistle seeds and then scurrying over the ground and up a tree before trying to spit all that stuff out again. Think about what it feels like to have a hair in your mouth and the sound and faces you make as you try to dislodge it. Now imagine the same sounds and faces on an adorable little mouse trying to spit out an entire mouthful of thistle fluff, which has to be far more worse than hair. This is the lasting imagery in my head, and I can’t tell whether I should be laughing or feeling regretful for screwing up the results of all that effort.

Tall thistle seeds. Nutritious, graceful, and not something you’d want to carry around in your mouth.

I really do feel badly about disturbing all those mice, though at least the weather was really nice as they sought shelter elsewhere. Hopefully, all the mice made their way back to those nests and didn’t mind that the host trees were now oriented horizontally instead of vertically. But while I feel bad about (temporarily?) dislodging them, and while I know it’s not nice of me at all, I’m even more distracted by what sound those mice must have made when they tried to spit out all those fluffy seeds…

‘Phleh! Phleh! Phleh!!’

This entry was posted in Uncategorized by Chris Helzer. Bookmark the permalink.

About Chris Helzer

Chris Helzer is the Director of Science for The Nature Conservancy in Nebraska. His main role is to evaluate and capture lessons from the Conservancy’s land management and restoration work and then share those lessons with other landowners – both private and public. In addition, Chris works to raise awareness about the importance of prairies and their conservation through his writing, photography, and presentations to various groups. Chris is also the author of "The Ecology and Management of Prairies in the Central United States", published by the University of Iowa Press. He lives in Aurora, Nebraska with his wife Kim and their children.

20 thoughts on “Another Example of the Value of Thistles

  1. Thank you for this post.
    As pollinator conservationists, we are trying to help land managers understand how to identify the different species.
    There are native and non-native thistles.
    Thistles are among the most important pollinator plants….offering food summer to fall.
    Also, wildlife eat them during cold winters when there’s not much else to eat, including hoofstock.
    Our horses love them for instance.

    Here’s a link to Xerces Society thistle ID factsheet.
    https://xerces.org/publications/guidelines/native-thistles-conservation-practitioners-guide

  2. While I agree that thistles are cool… I’ve even planted them…
    I’m appalled by your failure to value red cedar! Those aren’t the dreaded salt cedar, which isn’t even a cedar…
    I plant cedar to grow for posts and it does poorly for me… Luckily the black walnut and red mulberry do ok…
    A rot resistant wood is a valuable thing to have…

    • Stone, eastern redcedar isn’t actually a cedar either, it’s a Juniper (Juniperus virginianus). And it’s not that I don’t value the tree. It’s a great tree, and native to our state. And you’re right that it’s very rot resistant and makes great posts and other wood products. Unfortunately, due to too many years of fire suppression and a lot of human planting of the species, it has become problematic and has transformed huge swaths of grassland into woodland – decreasing species diversity and ecological function. Large parts of Oklahoma and Kansas grasslands are pretty well lost for good. Nebraska has lost some too, but still has a good chance to save some open grassland if we’re proactive. If my family and I hadn’t been cutting those little ‘cedars’ from our prairie for the last 20 years or more, that prairie would no longer exist.

      • Ok… Still appalled.
        There must be some way that you could use them… Say as an arbor… Or market the posts… Flood the Christmas tree market…
        I did google the botanical name of the cedars of Lebanon… And… Yeah… Different name….
        So jealous…

  3. Thanks for spreading the love of native thistles ! I spend a lot of time trying to educate gardeners on their value. I love them so much, I named my dog Thistle!

  4. In my backyard, white-footed mice build nests in the same way except using dandelion or sow thistle fluff. The voles are different. They shred stems into fibers to make their nests. At the end of the season, I pile stems I have cut from my gardens into my compost bin. The voles have a virtual paradise between the nest building materials and discarded vegetables.

    Have you tried using a torch to kill your eastern red cedars? When they are cut and left on the ground all sorts up weeds come up through them. This is not a problem when they are left standing. I have been creating frills and applying glyphosate to successfully control eastern red cedars while also leaving them standing.

  5. I always enjoy your blog posts. Often I learn something new, and spend a few moments admiring your photography, and sometimes you make me laugh out loud. Pleh, pleh!!
    Thank you!

  6. I love thistles! I wish there were more native ones here that haven’t been displaced. In Illinois, Cirsium arvense is an invasive plant that has really taken over in a bad way.

    Several years ago, we left a tiny patch alone because there were soooo many pollinators on that nasty patch, but it grew to CRAZY proportions by the very next year.

    I feel about thistles like I feel about cattails. I love them but I guess I have to hate the bad ones….oh well…

    Thank you for posting. We can’t let the bad take over, neither should we forget about the really important native thistles that everyone depends on.

    Perhaps restoration has a place for greater biodiversity with native thistles 🥰

  7. I really like tall thistle and have been tolerant of bull thistle but last year it decided to be more aggressive so I had to be more aggressive, too. Spotted with Milestone. Triclopyr also works sometimes. Hate when I accidentally hit a tall thistle. Musk isn’t a problem because it doesn’t compete well with healthy grass and forbs and we also have both the rosette and head weevil in Missouri. I thought the head weevil might work on the bull thistle but haven’t found them in them yet or maybe I don’t have them because I only have a couple musk thistles.

  8. Canada thistle, while admittedly invasive (and listed noxious in most if not all states) on disturbed sites, it has some of the best smelling flowers in the world. Roses have nothing on them. Bees and butterflies of all kinds swarm them when in bloom.

  9. I do like thistles – must the my Scots ancestors coming out. Prairie thistle – Cirsium pumilum – is especially nice in my prairies. Thank you again for the thoughtful essays.

  10. Great post, as always. However, you felt bad (not badly) about disturbing the mouse nests because you had regrets. If you’d gotten a thistle spine in your hand, your hand would have been feeling badly for a while because your feeling preceptors wouldn’t have been working up to par until you removed the spine.

  11. While I work hard to control Canada thistle on my Northern Tallgrass Prairie plot, ( a solid patch doesn’t have much diversity) it does appear that those missed or fairly well suppressed are probably contributing somewhat to other non-crop, non grazing values-they are probably filling a natural vacuum by absence of native forbs. There are often so many other Arci sources that in my mind complete eradication is not even feasible, less even possible… But the “law of the land” …… Native thistles though, can be pointed out though, as just that, and seem exist in scattered random plants and not a mono-culture.

  12. A prairie needs bison, wolves, and hunters…

    Good work, keeping us modern city-dwellers in touch with the prairie when we’re not adventurous to ramble out there in -1F! Ice bubbles, snow patterns, mouse nesting preferences… You never know what might be interesting and ecologically significant, unless or until you go out and look.

    Would you consider adding Disqus comment plug-in? Thanks.

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