Happy Little Fabaceae Family

In the last week, I’ve learned to identify over fifty prairie plants. We’re concentrating on learning the ones now in bloom in northern Iowa. Most of these flowers are distinctly different in color and shape, and this makes the identification easy. Three of these plants, however, are in the same family and look very much alike: veiny pea, American vetch, and marsh vetchling. They all have similar leaves and pinkish- purple flowers. At first these three plants perplexed me. How would I ever tell them apart? I’ve since learned the secret.

In order to distinguish among the plants, first, look at the stipules. A stipule is a pair of tiny leaf-like appendages at the base of the petiole. “Petiole” is a fancy word for the little stalk that attaches the leaf to the stem. The stipules in the veiny pea and the marsh vetchling are plain, but in the American vetch, they have teeth. Rough stipules are a sure sign of the American vetch.

If the stipules are not jagged and toothy, the plant may be either the veiny pea or the marsh vetchling. A quick guess could be made between the two through observation of the surroundings. The veiny pea grows more readily in dry areas while the marsh vetchling grows--you guessed it--in marshy, wet areas.

But to be sure, check the plant's stem. If the stem is relatively square, it is likely a veiny pea. If, the square stem has a pair of wings and appears almost two dimensional, ribbon-like, farther down on the plant, it is the marsh vetchling.

Puzzling specimens like these make plant identification much more fun. Even the same species can look differently and so I’ve found that I’m learning largely through comparison. I really have to get down there in the grasses and look carefully at the plant before making a judgment. It can be tedious work, but is also very satisfying!