Yellowjackets munching Dutchman's Pipevine seed pods!

Dutchman's pipevine - Aristolochia californica

This year we had a bumper display of Dutchman's pipevine flowers. The vine shown above is growing up through a rambling rose.

This plant is the sole larval food of the Pipevine Swallowtail butterfly in our region (sole native larval food anyway), so gardeners are growing it in an attempt to create a butterfly "corridor." The Pipeline Swallowtail is not seen in Santa Cruz County any more due to lack of larval food. The plant has a toxin that makes the butterflies toxic (much like milkweed makes monarch's toxic to predators).

It's also a fun vine to grow. I've got several going rampant now, some sprawling along the ground. They seem to tolerate fairly dry conditions but prefer moisture and afternoon shade. Grow to fifteen feet or maybe a bit more when they ramble over the ground. They like narrow supports like wire (or rambling roses!) to grow up rather than a wood trellis.

Somehow, I had never noticed the very interesting seed pods on Dutchman's Pipevine before this year. (Or maybe last year, to be honest.) The one below is about two and a half inches long and quite solid.

And I'd and certainly not noticed what happens to them after splitting open, until today!

Yellow jackets were swarming all around, munching away inside the seed capsules. Below you can see the start of the munching. I believe it starts only after the seed capsule starts to split open at the bottom.

Below - This one has a few seeds inside. You can see the six chambers (carpels, I think in botanical terms).

The seeds are quite soft. So I wonder if they are also going into the yellow jackets' tummies.

I've put a net bag (the kind you put party favors in) over one to be sure I'll get some seed. Seeds need no pre-treatment, but I read in a forum that they can take up to three months to germinate.

Fun in the garden!


Byddi Lee said…
I love love love my Dutchman's Pipevine. Shade and drought tolerant! What a sterling combination. I've never noticed the seed pods before. You've motivated me to go out and take a look. I wonder does the action of the yellow jackets help the seeds disperse? Are they fully mature at this point and viable? The pods did look a little green and I'd imagine that a pod ready to disperse seeds would be papery and brown. Very interesting post.
Country Mouse said…
Thanks, Byddi -- It could be that since the pods were just starting to split, the seeds were still a little immature. The one I brought in, the one that was just a little split open at the bottom, dried up really quickly, though, in a matter of a day or less. It split all the way open and the seeds dried up. I'm still not sure if the wasps munched the seeds, but I suspect they might well have.

Just popped out to check - none of the green ones has split lately. Even though we had temps into the low nineties yesterday!
I agree, it's a wonderful plant for me too!
John Albright said…
More about the yellowjacket phenomenon -- I live a bit further north than you up in Shasta County, where pipevine is pretty common and the pipevine swallowtail is probably the most noticeable butterfly around here that has any "cool" factor going on. I have been picking ripe fruits to collect seeds to scatter in areas adjoining new residential developments that are displacing the habitats for the vine and ergo the butterflies. I had noticed in that process that some of the pods on the vines would be split open only slightly, but completely devoid of any seeds. I was curious how the seeds, which are like small sunflower seeds could have been properly aligned and propelled to get out of these slits.

I think that the mystery was solved for me yesterday as I had a paper bag with several dozen of the pods that were ripe, but had not yet split, on my patio to finish opening so I could get at the seeds and they would stay warm and dry because I have had issues with mold storing them in poorly ventilated areas. Normally I do this in my garage, and therefore knew that I should have had many hundreds of seeds as a result of going through this process. However, upon checking the bag after most of the pods had split I found only a handful of seeds.

Furthermore, I found that the appearance of my face over the bag caused several yellowjackets to fly out of the bag. I had previously noticed that, upon splitting the pipevine pods emit a very distinctive foul odor. I suspect that this is "by design" to attract the yellowjackets as a method of dispersal for the seeds. This led me to a Google search, which led me to your blog. As a bug and plant enthusiast I find this whole idea very intriguing.

I know that there is one chemical, heptyl buterate, that smells pretty bad and is used as an attractant in yellowjacket traps. The pods don't smell exactly like that to me, but there could be other chemicals involved. I plan to get some more pods and spend some time looking into that bag to try to figure out exactly what the interaction is there. I still don't know if this is a widely known phenomenon, or if it is really what I think it is for that matter.