Sunday, September 13, 2015

Twining Peas

I had a confusing summer of twining, prostrate pea-family relatives that was partially of my own doing. I had planted some seeds, and I had not done a good job of labeling them. Then Mother Nature decided it was time to set me straight on some similar plants.

You see, when it comes to pea-family plants (Fabaceae is the family), I tend to be a “lumper.” In the past, if a plant had 3 leaflets, and especially if it also had pink flowers, then I’d say “it’s probably a Desmodium.” The tick trefoil genus Desmodium has lots of species, is rather commonly distributed, and frankly most people aren’t interested in going any further with identification than that. So it was always a handy answer, but I should have tried harder.

What I hope my Apios americana looks like one day
This year started out with seedlings and pots of transplants for which I had specific hopes. I had gathered seeds of groundnut (Apios americana), Atlantic pigeon-wings (Clitoria mariana), as well as a transplant of butterfly pea (Centrosema virginianum). I was excited to introduce all of these plants to my yard.

Groundnut, in a properly labeled pot, sprouted with leaves with 3 leaflets and grew in that fashion until late August. By then I was sure that my pot had been mislabeled after all since groundnut has more than 3 leaflets per leaf. Finally, the plant produced a leaf with 5 leaflets. Hooray!

In spring, I transplanted what I hoped was a pot of pigeon-wings into a planter with other native perennials. It happily twined all summer and even hosted a couple of caterpillars. Yay! Bloom buds finally formed this week and it is not the pigeon-wings. It is hog peanut (Amphicarpaea bracteata), easily recognized thanks to a recent Facebook post by the Georgia Botanical Society. I have no idea where that came from! So I am 1-1 on plants that I tried to cultivate and the butterfly pea is nowhere in sight (or is it?).

Hog peanut (Amphicarpaea bracteata)

Meanwhile, pink flowers were showing up elsewhere in the garden, and I decided to identify a particularly robust, twining vine that was developing smooth, plump pea pods in the front bed. Turning to my plant identification key for Desmodium, I ran into a snag immediately. Nowhere did it say that the fruit should be a single pod. Tick trefoil fruit needed to be a segmented pod-like structure (where each segment can break off and stick to you).

Desmodium seeds are segmented
I put the puzzle aside, thinking vaguely it could be a Lespedeza (bush clover) instead. A week later, the Internet came to my rescue. Someone else posted a picture of the plant on Facebook, and it was identified as milkpea (Galactia). Using that information, I confirmed that my plant was indeed Eastern milkpea (Galactia regularis) – a plant I’d never even heard of.

Milkpea (Galactia regularis)

Lespedeza repens
When I came across the next sprawling pink flower, the Lespedeza possibility was still on my mind, so I decided to examine it a bit more closely. It turned out to be creeping bush clover after all (Lespedeza repens) with tiny but single seeds. So now I am 2-and-2 for the pea family, but I feel I am all the better for the experiences.

This summer has also made me take a closer look at what I know to be Desmodium plants and I believe I have a better idea about those too. First, of course, they need to have segmented fruit, and second, they really don’t twine very often.

So from now on when I find one of these mystery plants, I have a better answer: It’s in the Fabaceae family.


  1. Enjoyed this. I get all confused also.

  2. Good luck on the apios.
    Last year I finally located a source of indian ground nut, but the transplant did very poorly in the pot, eventually disappearing completely... soo... I'm waiting for the seeds to ripen on the wild patch, and try those.
    Hog peanut did fine for me (this year), too...
    I have clitorea and centrosema growing as naturals, can save you seed and you can try again...
    As cool as desmodium are... maybe take a look at tephrosia :)