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Thistle: is there any benefit to this often-maligned plant?

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Jeff Beauchamp Photo Thistles are an underestimated source for Monarch butterflies and Swallowtails like this one who landed on a Wright’s Marsh thistle at the Bitter Lake National Refuge.

By Jeff Beauchamp

wildlife biologist

Bitter Lake National Wildlife Refuge

I have to be honest. My first instinct when I see thistle in my yard or along the roadway is to pull it out of the ground and get rid of it. It is ingrained in my soul: thistle = bad! I’ve often wondered if there was any environmental benefit to this prickly plant. Surprisingly, I found the answer to be, yes.

In New Mexico, we have 12 native thistle species that occur in a host of different habitats. Two of those 12 occur in wetland habitats and are afforded some state and federal protection due to their limited population size and loss of habitat.

At Bitter Lake National Wildlife Refuge, we have one of those rare thistles — the Wright’s Marsh thistle. You can find it blooming on the middle tract of the refuge toward the end of August through September. The flowering is perfectly timed to feed migrating Monarch butterflies and birds as they make their way south.

New Mexico also has a few thistle species that are not native to the state. Three of the most common invaders are Canada, musk and bull thistle. Interestingly, Canada thistle is not actually from Canada, but originates in Eurasia and is oftentimes referred to as creeping thistle due to the creeping nature of the roots — a good way to identify this unwanted species. If you are interested, the Native Plant Society of New Mexico published a great field guide to identify the various thistle species, both native and nonnative, in New Mexico. The guide can be found at npsnm.org/education/thistle-identification-booklet.

Back to my original question and how the answer could possibly be yes. First, thistles provide important food, both nectar and pollen, for a number of different pollinating insects, from bees to butterflies (see pictures). These same insects pollinate our farm fields in and around Roswell. Even hummingbirds will feed on thistle nectar. Insects aren’t limited to nectar and pollen, though. Some insects will eat thistle leaves and stems. As the thistle plants mature and start to seed out, more birds get in on the foraging fun; both finches and sparrows are known to feast on thistle seeds and, out here on the refuge, blackbirds are often seen foraging on thistle seeds in the fall. Finally, even some burrowing mammals are known to eat the roots of thistles.

So, here is my pitch to you: Before you pull out that thistle, make sure you aren’t killing a native plant that is an integral part of the environment. And if you are feeling up to it, plant some native thistle in your garden and watch as the pollinators swarm — they need it.