The Problem with Invasive Plants

What are invasive plants?

Invasive plant species are plants introduced into an area where they were not already naturally growing. For example, bush honeysuckle is native to Asia, but was introduced to the United States and has spread rapidly throughout Missouri and other states.

Why are they a problem? They look fine to me.

Many invasive plants are attractive, and invasives like bush honeysuckle green up early in spring. However, they can spread so rapidly that they outcompete native plants like wildflowers and oak seedlings. Native plants form the foundation of the web of life. For example, the caterpillars of more than 500 different native butterflies and moths feed on oak leaves. Many of these insects are important food for baby birds. If invasive plants crowd out oak trees, for example, the entire food chain can suffer.

Many Missourians make a living directly from the land. Invasive plants can negatively impact their livelihoods. For example, invasive plants can invade cattle pastures, reducing the amount of forage cattle have to eat. Invasive plants can prevent oak and hickory trees from growing, which impacts Missouri’s significant forest products industry.

Hikers, hunters, anglers, boaters, birdwatchers, and others who enjoy Missouri’s outdoors have fewer opportunities for outdoor recreation when invasive plants degrade streams, hunting habitat, and other aspects of the natural world. Collectively, outdoor enthusiasts contribute millions of dollars to Missouri’s economy, but invasive plants threaten the outdoor industry.

I see some invasive plants in woods, but Missouri has plenty of other places for native plants and animals, right?

While Missouri has an abundance of wild places, invasive plants have been found in almost every prairie, forest, woodland, stream, and other habitat in our state. Wildlife needs native plants and can suffer without them.

I have a Bradford pear tree in my front yard, but it isn’t spreading, so how can it be invasive?

Each cultivar of ornamental Callery pear trees, including Bradford and Chanticleer, among many others, is sterile, but when pollen from one cultivar is transferred to the flowers of a different cultivar, and small fruits form with seeds inside them, birds eat and carry the fruits, spreading seeds. This is how invasive Callery pear, bush honeysuckle, and many other invasive plants spread.

Other invasive plants spread by rhizomes or runners, increasing populations in a single area. In other cases, the seeds of invasive plants are carried by wind or water, and plants can become established far from parent plants.