Day 159: Fifth Clover?

Earlier this year I spotted a new plant growing near the end of my driveway.

Looking at both the flower heads and leaves, I thought this mystery flower was likely to be a clover. Going on that assumption, I searched online for “yellow clover.” The search returned a lot of hits, because there are several varieties of yellow clover, called “hop clovers” or “hop trefoils.” There is also a related plant, black medick, that is said to look similar, so similar that it, too, is sometimes called “hop clover.”

Unsure which plant I had found, I put the pictures of my mystery flower aside. But I kept an eye on that patch of flowers as it continued blooming and, later, started to seed. The most reliable key to distinguishing between hop clover and black medick, I have learned, is the seed heads. The flowers of hop clovers are said to puff up as they mature, coming to resemble hops, which is how they got their name. Then they turn brown, much like white clover flowers do. Black medick develops a distinctive cluster of seeds that turn black as they mature. (This webpage, though specific to Cape May, is a handy guide to some common clovers and clover relatives. It includes pictures of the flowers and the seed heads.)

Now that my mystery plant has gone to seed, it’s time to make the identification.

Surprise! My mystery flower is black medick. I’m a little disappointed, because I wanted another clover to add to my list, but I’m also glad to have learned about a new type of plant. Black medick is, like so many of the plants in my yard, considered to be a weed, but as far as weeds go, it’s a good one. As a member of the legume family, its roots host nitrogen-fixing bacteria, and over time it will improve the quality of the soil in which it grows.