Black medic (Medicago lupulina)

Black medic. It’s a weed I’ve known for what feels like forever, I teach students to correctly identify it every year in the weeds lab, but other than that it is one I’ve paid very little attention to until recently. As in this week.

Black medic (Medicago lupulina), a member of the legume family, is a common weed in yards and gardens.

This week the temperatures haven’t been so terribly hot, like they have been for a lot of the summer, which means we’ve been playing outside on our little patch of lawn. I say lawn in the most liberal sense of the word. There’s a bit of grass, some of it alive. And a lot of black medic.

You’ve probably seen black medic before. And you’ve probably thought that it appeared to be a lot like clover, but with yellow flowers. And, you’d be right…it is a lot like clover. They both have trifoliate leaves, they both have those typical pea-family flowers. Being legumes, they also both fix nitrogen (convert the nitrogen in the atmosphere into a usable form for the plants). And they are both very common lawn weeds.

But where I don’t often give clover much thought either, after this week of playing in the black medic patch, I’ve decided I prefer the clover. The leaves and stems are softer, not so coarse and almost woody like the black medic. Though clover can form large patches in the lawn, it doesn’t seem (to me, anyway) to be as intrusive. Also, when the clover flowers mature, their seeds/seed pods are much less visible and distracting.

The dark black seed pods mature from the top down – in the same cluster you can often find black pods at the top while the lower ones are still green.

It was really these seeds (ok, technically they are just the seed pods, but for now we’re just going to call them seeds) of black medic that caught my eye and attention this week. I knew that it had black seeds, hence it’s name. But I’d never paid much attention to them before. This time, though, they seemed to jump out at me and so I picked some off and started looking a little closer. And then, like any self-respecting weed scientist, I went inside, got a little zip-top bag, and returned to the patch to collect more seeds. You never know when you’re going to need some weed seeds for an experiment.

As I collected my seeds, I noticed some things. First, they don’t all mature and turn black at the same time. On the same cluster, there can occur various stages of maturing seeds, but the ones at the top mature first. I was also struck by how similar black medic seeds are to alfalfa (Medicago sativa)ย seeds, though less coiled. When I stopped to consider that they are both in the genus Medicago, that didn’t seem so surprising after all. And I also noticed that though it grows prostrate in my lawn, if given the opportunity, it will grow upright like its alfalfa cousin. None of these are new or groundbreaking discoveries about this lowly plant, but they were new to me because I was looking with new eyes.

Perhaps the most important thing I learned this week wasn’t actually about black medic at all. Perhaps the lesson is that even with all the changes this last year has brought – mainly becoming a mom and quitting full-time work and wondering many times about whether I’m the same me as before – I recognized that as long as I keep my eyes open and keep asking questions, being a mom and being a scientist aren’t mutually exclusive. Even if the only “science” I am doing in a day is becoming a little more familiar with my patch of black medic.


  1. I like your discovery that ties everything together. I’ve also found it exciting to watch my kids learn something new (either because I taught them, but usually just by themselves figuring out the scientific method). You’re doing great! And Gracie is lucky to have you s her mom.

  2. Interesting! I’ve definitely seen some of this in our lawn. You can keep doing posts about lawn weeds so I can identify them all, but it would take a while. There’s a lot ๐Ÿ˜‚

  3. So amazing! I love the pictures, the information and the personal discovery!

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