Yellow Sweetclover

White Sweetclover

It should come as no surprise that many of North America’s most prolific wildflowers are invasive species.  Invading flora that flourish by definition displace native plants.  And since I’ve started out discussing common wildflowers, that means a lot of talk about plants that hitched a ride over the wide oceans- intentionally or unintentionally.  And here’s another, but there’s some good news to talk about too.

In late May, a yellow wildflower started to bloom in central Ohio- tiny blooms growing along the terminal spikes of their stalks.  The leaves are small and divided into 3 leaflets at the end of a stalk.


This is Yellow Sweetclover, which is a member of the legume family.  This family includes such familiar foods as peas, beans, lentils, and peanuts.  The blooms are interesting to look at, but it helps to have a magnifying glass.

This plant was joined by White Sweetclover, which started blooming here in mid-June.  Both White and Yellow Sweetclover are similar species, similar enough that some scientists think that they are actually different varieties of the same plant.  Both of them frequently grow in sizable colonies, and prefer sunny locations such as fields and roadsides.  They grow in all 50 states of the US and in most of the world for that matter.  If you crush the leaves, you’ll smell a sweet scent reminiscent of the countryside.

These plants come from Eurasia, and first came to North America in the 17th century.  They were planted here on purpose, but before I talk about the benefits of these plants, let’s cover the negative points.

As widespread and common invasive species, sweetclovers of course displace native plants, replacing biological diversity with tendencies towards monoculture (very little variety).  They are hardy plants, drought-resistant, and their seeds can remain viable in the ground for 30 years, making them hard to control.  They are a threat to prairie restoration projects, and can cause sweetclover poisoning in livestock if they eat enough of its moldy fodder.  This condition causes internal bleeding and death.

Now for a little good news.  The reason sweetclovers were brought here from Europe is that they make good animal fodder in the form of hay- just make sure the hay doesn’t get moldy!  They also are a significant source of nectar and pollen for honey production; bees frequent their blooms, and the resulting honey produced is of high quality.  Their hardiness can have beneficial effects upon the soil they are planted in because their roots open up the subsoil.  They fix nitrogen in the earth, rejuvenating it for crop production; also, their roots hold the ground in place, discouraging soil erosion.  As a herbal remedy, these plants were used in the past to treat hypertension and insomnia.  Sweetclovers are harvested for a substance called coumarin, which is an anticolagulant produced from the plant by molds and then used in rodenticides.

It’s nice to see an invasive plant that has a good and useful side!  And it’s all too easy to take such plants for granted as we drive past them along roadsides, or stroll past them in meadows.  Their blooms will be with us until early autumn.