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Are those bugs? Understanding the Tick Trefoil

Have you looked down at your pants after a hike and wondered what all those little, flat green things are? Where do they come from?

I’d like to introduce you to Tick Trefoil, members of the genus Desmodium. We have 17 species of Tick Trefoil in this area. The genus name Desmodium if from the Greek desmos, meaning “a band or chain”. This is in reference to the bead-like seedpods that break apart when brushed against. The individual seeds are covered with tiny hooked hairs that help it hook onto anything passing by. It works very well as a mechanism to spread Desmodium, a legume. The name “Tick Trefoil” is based on the seeds that cling like ticks and the 4-7 trifoliate leaves on each stalk.

Tick trefoil blooms from July to September. The blooms are pinkish-purple and small. They are quite easy to miss unless you are specifically looking for them. When you do find them, you wonder how you could have possibly not seen them. They tend to be everywhere and prefer sunny areas, wasteland and cleared areas along roadsides.

Some Desmodium are known to be medicinal. Studies have shown the value of this species, as well as other legumes, as a native forage for pasture use. Wikipedia states that “while not as easily digestable and protein-rich as some non-native legumes and grasses, the panicled-leaf tick trefoil can be a good source of protein-based fodder for livestock during the warmer months of the year.” Tick Trefoil can be used as a living mulch or green manure as they are able to improve soil fertility via nitrogen fixation.

The species of Tick Trefoil you find can be extremely difficult to identify. Different species throughout the world have been used in medications to treat dysentery, rheumatism, pyrexia, wounds, coughs, malaria, hepatitis, hemoptysis, and more. They have even been used to repel insects!

As you meticulously pick the seeds of Tick Trefoil, one by one, off your hiking pants and boots don’t forget that there are also some positive attributes to this legume. Tick Trefoils are pollen producing plants, and have no nectar. So, the flowers will only attract bees. Six different species of long-tongued bees frequent this flower (Robertson, 1929). This flower is open pollinated, meaning the wind will pollinate the flower in absence of bees. It is a host plant to 3 different butterflies/skippers (Eastern Tailed Blue, Hoary Edge Gray Hairstreak, Silver-spotted Skipper).

In addition to bees and butterflies, numerous other insects visit this plant including leaf miners, weevils (eat seeds), and gall flies. Even Japanese Beetles have been found feeding on the foliage.

Plus, the leaves are browsed upon by deer and rabbits. The seeds are eaten by numerous game birds and mice, including turkey, quail, grouse and the foliage also provides cover to birds and mammals.

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