Story by Annie Krueger and Tom Weissling
Lead Photo by Anna Swerczek
Let’s talk about milkweed.
When you hear the word “milkweed” you probably think about monarch butterflies. Maybe you’ve even spent some time looking for monarch caterpillars on plants. But what you might not realize is just how important milkweed is to many other creatures and what role milkweeds play in the environment.
In addition to contributing to plant diversity in many different ecosystems, milkweeds are crucial to the survival of a variety of animals and have been historically important for humans. We’ll take a closer look at some of these roles. But first, the basics.
Milkweeds are perennial plants native to the U.S., parts of Canada, Mexico and Central America. They can be found in nearly every habitat from marshes to meadows and even deserts. You’ve probably driven by large stands of milkweed on the side of the road. There are more than 130 species of milkweed, and they vary tremendously in appearance. Some species have large broad leaves while others have small narrow leaves. Some are low growing while others can grow more than 5 feet tall!
Milkweeds are aptly named for the milky, white sap that runs through their stems and leaves. Unfortunately, the other half of its name, “weed,” evokes a wide range of responses from people, including a desire to kill these plants.
By definition, a weed is nothing more than “a plant out of place.” Milkweeds are not listed anywhere in the U.S. as noxious weeds, nor are they invasive. Still, people ask, “What good is milkweed?”
The answer to that question is large indeed. Like all plants and animals, milkweeds have an important position and role in urban, agricultural and natural areas. They serve as shelter, nesting habitat, and as a food source for a multitude of animal species.
Interestingly, animals that feed directly on milkweed, such as monarch caterpillars, are pretty unique. The white sap these plants produce contain toxic compounds that should kill monarch caterpillars if eaten! But instead, the caterpillars have evolved ways to withstand the toxins and many are able to store them internally to protect themselves from being eaten in the same way the milkweed plant does. Animals that cannot withstand the toxins avoid the plants or eat so little that they are not affected.
Just as monarchs make use of milkweeds and their toxins, humans have utilized these plants for centuries.
Native Americans realized milkweeds could be used to treat a variety of ailments. Externally, sap was used to remove warts and relieve symptoms of poison ivy. By boiling the plant, they found ways to remove milkweed toxins in water, using the extracts to suppress coughs, sore throats, and to treat typhus fever and kidney disorders. After several rounds of boiling, stems, buds and immature pods could then be eaten.
Some of the most impressive uses of milkweed come from the white fluff (floss) inside of pods which was used to stuff pillows, mattresses and blankets. In our modern era, the insulative and water-repelling properties of the fluff have been discovered and used in many ways. In World War II, the buoyancy of milkweed fluff was put to the test when it was used in military life jackets instead of kapok. In addition, the fluff has excellent oil absorbing properties and can be used to soak up spilt crude oil while repelling water. The fluff has also been used as insulation in jackets worn by climbers ascending Mount Everest.
For as long as milkweed plants have been around, they have been crucial to the survival of a variety of animals, including hundreds of insect species that use the plant for food or shelter. Their flowers are visited by many species of native bees, wasps, and other nectar-seeking insects. Their leaves and roots are food for numerous beetles, caterpillars and true bugs. Insects feeding on plants serve as food for predators and parasitoids, which promotes ecosystem stability and species diversity.
Insects in these milkweed communities also serve as a critical food source for a number of birds, such as pheasants and quail.
Insects are a critical part of every food web but due to habitat loss and a lack of nectar or other food sources, many species are in decline. Pollinators, especially native bees, have lost food and shelter across the U.S. and have declined at an alarming rate. Planting milkweed (this summer Pheasants Forever and Quail Forever will surpass a billion seeds in the ground since seed program inception) can help to establish an entire food web, not only supporting monarch butterflies but also contributing to the survival of countless other insects and birds – including pheasants and quail and upland songbirds.
Annie Krueger and Tom Weissling work in the Department of Entomology at the University of Nebraska-Lincoln.