Tag Archives: penstemon

The Penstemon Lumberjack Mystery

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Shell-leaf penstemon in a restored grassland at the Platte River Prairies back in 2021.

One of my favorite wildflowers is the spectacular shell-leaf penstemon (Penstemon grandiflorus). It’s one of the showiest of the opportunistic wildflowers in our prairies. Shell-leaf penstemon thrives under heavy grazing, in sandy and/or low-productivity soils, or other places where most other plants struggle. Every year, as the month of May progresses, I watch closely for the first blooms so I can get out and photograph them.

Which is why it really ticks me off that an unknown entity chops a bunch of them down every year. I don’t know who’s doing it, I don’t know why they’re doing it, and it’s incredibly frustrating. I’m sorry to lose the flowers, but my biggest resentment is that I can’t explain what’s happening.

What’s particularly confusing is that whomever cuts the top of these plants off with their teeth doesn’t appear to then eat anything it removes. The tops of the plants are just left lying around.

It’s almost as if someone is annoyed by the excessive height of the plants and has a compulsion to hack them down and keep them short. Or maybe they just hate beautiful flowers. But if that’s the case, there are plenty of other gorgeous wildflowers in the prairie they could attack and I’ve never seen this “cut and leave it lie” behavior with any other plant species in our prairies.

Having said that, I guess prairie dogs do chop plants down around their towns, but we don’t have prairie dogs at the Platte River Prairies. Unless they’re really, really sneaky prairie dogs. I’m not dismissing any possibilities right now, but that one feels pretty far-fetched.

What is happening? Why would some animal nip the top off a penstemon plant and then just leave it there??

My top candidates are black-tailed jackrabbits, but thirteen-lined ground squirrels are high on that list, too. It also feels like the kind of thing a cranky, vindictive white-tailed deer might do, but the sharp angled cut feels more like rabbit or rodent. Google says pocket gophers can reduce the size of penstemon populations, but they’re underground foragers, so they don’t seem likely.

To be clear, I don’t begrudge any animal its search for food. By all means, eat all the plants you want to eat! In fact, it makes me feel good to know that our prairies and stewardship work are providing sustenance for wildlife.

But this looks like wanton destruction, not foraging. Apart from disliking the height or beauty of the plant, the only other explanation I can come up with is that something wants access to the liquid inside the stem. Are rabbits cutting the tops off the plants and then sipping xylem and/or phloem out of the stems like a kid with a soda straw?

Now that I’ve got that visual in my head, if that’s what’s going on, what I’m most mad about is that I’ve not gotten to watch it happen. It sounds adorable.

You can see the tops of the plants lying next to the bases they were nipped off of.
The sharp angled cuts look like what I’d expect from a rabbit or ground squirrel.

I’m hoping those of you who read this will have some helpful information for me. Have you seen this near you? Have you seen it with other plants besides shell-leaf penstemon? Any idea who would do it, or why? Do you have friends who might know? Acquaintances?

I don’t want to pressure you, but honestly, if we can’t use this blog’s reach and influence to solve a simple mystery like this, why am I wasting my time with it? I could do other things with my life. For example, I could…

Hm. Ok, I retract that threat.

But still, someone out there has to have an explanation, right? I’ve been seeing this phenomenon for years, so it’s not an isolated incident. I’m also pretty sure it’s not just one ill-tempered individual jackrabbit with a bad attitude about penstemon. As far as I know, jackrabbits don’t usually live longer than five years and I’ve been watching this for more than a decade.

Thanks in advance for your help. Any reporting will be appreciated. If you’ve seen something similar, tell me both where you saw it and any relevant details – plant species, topography, soil type, local rodent/lagomorph species, most popular local sports team, etc. We don’t know what will constitute key information, so the more the better. If you yourself don’t have anything to report, please pass this post on to others who might know something. Let’s figure this out!

Photo of the Week – May 26, 2017

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Shell leaf penstemon (Penstemon grandiflorus) is one of the showier wildflowers in the Platte River Prairies during late May and early June.  It is most often found in dry soils and where the surrounding plants aren’t overly competitive.  We often see populations increase after droughts and grazing events and then decrease again as grasses recover their vigor in subsequent years.

Shell leaf penstemon has big showy flowers that are just the right size for bumblebees, but are used by other pollinators as well.

For years now, I’ve been periodically coming across patches of shell leaf penstemon plants that have been decapitated by a rabbit or something.  That wouldn’t be surprising except that the top of the plant is usually just lying next to the plant uneaten!  There is a single angular slice in the flowering stem, usually well below the bottom-most flower, and the entire flowering stem just (apparently) falls to the side.  I’m at a loss to explain this.  I don’t know if an animal is doing this to lick the juices out of the stem for some reason?  I honestly can’t think of any other good reason for what I’m finding – not that juice licking is a very good reason…  I’d love to hear from someone who knows the answer to this.

Yesterday, Nelson (our land manager) and I were touring a colleague from Wisconsin around one of our prairies and found a patch of decapitated penstemon.  As we were discussing the mystery, Nelson grabbed one of the stems and saw what he thought might be a black stem-boring insect.  As we peeled apart the stem to see it, it turned out to be a small black wasp or bee that Nelson had apparently squished when he picked up the stem.  Before I could get a very good look, the wind blew the deceased insect off the stem and down into the grass at our feet.  I didn’t worry too much about it, but as we continued to peel open the stem, I wished I’d tried to recover the insect.

Here is the detached flowering stem Nelson picked up.

The penstemon stem was stuffed full of flies.  Flies of all shapes and colors.  There were more than 20 of them, separated intermittently by wads of dried plant material.  Based on what we found, I guessed the insect we saw, and then lost, must have been a wasp and that it was laying eggs in the stem and provisioning them with flies.  I took the stem home to photograph it and then sent the photos to my friend Mike Arduser, who knows everything about bees, and an awful lot about wasps and other insects as well.

Here is a close-up photo showing the diversity and abundance of the flies jammed into the stem. I looked, but didn’t see the eggs that must have been there.

Mike said the insect was very likely a wasp in the genus Ectemnius that usually uses flies as the food source for its larvae.  They frequently excavate the pith out of twigs and other stems.  Based on the behavior of other wasps, I assume the flies were paralyzed, not dead, and that there was an egg laid with them, but I didn’t actually see any eggs.  According to Mike, Ectemnius wasps have a kind of “cuboidal” shaped head and the various species are between 6 and 14 mm in size.

I’m very certain the wasp wasn’t responsible for cutting the flowering stem off the penstemon, but it was pretty interesting to see something taking advantage of the destruction.  I didn’t see any other stems with similar nests in them, but I’ll sure keep an eye out for that in the future…

Now if I can just figure out who or what is decapitating our penstemon plants, I’ll be satisfied.  Until the next mystery comes along.

PLANT GAME RESULTS:

On the whole, you did pretty well on the plant game this week.  I tricked most of you on the first one, but the majority of you guessed correctly on the second and third questions.

On the first question, 161 people voted (as of this afternoon) and almost 50% chose Candy Lovegrass as the fake name, which is wrong – it’s a real plant.  Look it up if you like.  The actual fake name in that list was Clark’s Blisterpod, which came in 3rd at 22%.

More people (212) were bold enough to guess on the second question, and 50% of you were correct that Bully Pulpit was the fake plant.  However, about 1/3 of you guessed Beefsteak Plant, which sounds fake but is real – and invasive in at least some places/situations.

On the third question, 172 people voted, and 47% correctly identified Slipper Cherba as a fake plant name.  Autumnal Water Starwort and Beaked Ditchgrass were second and third in the voting with 25% and 21%, respectively.  I really thought more people would go for Beaked Ditchgrass, but what do I know?

Thanks for playing my goofy game.  The hardest part of putting it together is coming up with names that are weirder than the real ones…