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Wyoming Noxious Weeds


Wyoming's beautiful landscapes are home to stunning natural beauty, but they are also threatened by a persistent challenge: invasive weeds. These plants grow quickly and spread easily, disrupting the delicate ecological balance of the state.

Field Bindweed

Field bindweed is a common and troublesome weed in gardens and agricultural fields in North America. It has heart-shaped leaves and delicate pink or white trumpet-shaped flowers, but it is a vigorous and invasive plant native to Europe and Asia. Field bindweed spreads rapidly through its underground rhizomes, which can choke out desirable plants and reduce crop yields.

  • Field bindweed has an extensive root system and vigorous vine-like growth
  • The weed grows rapidly and has the ability to twine around plants, making it difficult to control

Canada Thistle

Canada thistle is a perennial weed native to Eurasia that has become invasive in North America. It is a member of the sunflower family and is characterized by its spiny leaves and stems, and its purple or white flowers. It can grow up to 6 feet tall and can form dense stands that crowd out native plants and spread both by seed and by root. Seeds can be dispersed by wind, water, and animals, while root fragments can sprout new plants, even if they are very small.

  • It easily out-competes natural ecosystems
  • It has deep and extensive root systems that make it difficult to eradicate

Leafy Spurge

Leafy spurge is a noxious weed that has invaded Wyoming. It can grow up to four feet tall and has long, narrow leaves and yellow flowers that bloom in the summer. Leafy spurge contains a toxic sap that can irritate the skin and eyes of livestock and humans, and it can cause health problems for animals that eat it. If you see it on your property, remove it immediately. You can do this by hand, mowing, or using herbicides.

  • Leafy spurge is highly invasive
  • The weed produces a milky sap


Quackgrass can quickly take over gardens and agricultural fields if left unchecked. It spreads rapidly through its rhizomes, which are underground stems that can send up new shoots. Controlling Quackgrass is a challenge, but it is possible with diligent management practices. One of the most effective ways to control it is through regular cultivation. Cultivation involves digging up the soil to disrupt the weed's rhizomes. This can be done with a shovel, hoe, or tiller. Cultivation should be done repeatedly throughout the growing season to prevent the rhizomes from regrowing.

  • Quackgrass has long, flat, blade-like leaves and can grow up to 3 feet tall
  • It is resilient to mowing and can regrow from its rhizomes even after being cut down making it difficult to control

Ox-Eye Daisy

The ox-eye daisy is a charming wildflower that adorns fields and meadows with its radiant white blooms and vibrant yellow centers. A favorite among pollinators, it attracts bees and butterflies to its nectar-rich blossoms. Its hardy nature allows it to thrive in a variety of conditions, making it a resilient and delightful addition to natural landscapes. Gardeners often welcome it for its timeless beauty and ability to brighten up any outdoor space. It is a very adaptable plant and can be found in a variety of habitats, including meadows, prairies, woodlands, and even disturbed areas. Once it invades, it can displace native grass and other plants, reducing the quality of available land for agriculture and grazing.

  • Ox-eye daisy is a perennial plant, meaning it is enduring.
  • It has been naturalized in many parts of North America and is often seen in roadside ditches, fields, and gardens.

Scotch Thistle

Scotch thistle is an example of the devastating impact invasive plants can have on native ecosystems. This thorny plant, native to Europe and Asia, has made its way to other parts of the world, including North America and Australia. Its rapid growth, prolific seed production, and ability to thrive in diverse conditions make it a particularly aggressive invader. Scotch thistle quickly crowds out native vegetation, reducing biodiversity and disrupting local ecosystems. The overshadowing of native plants deprives native fauna of their traditional food sources. As a result, the spread of Scotch thistle challenges the balance and health of the habitats it invades.

  • Scotch thistle follows a biennial growth cycle, with the first year dedicated to vegetative growth and the second year focused on flowering and seed production
  • The spiny nature of Scotch Thistle can be a hazard to livestock, causing injury when consumed

Perennial Pepperweed

Perennial pepperweed is a tall, perennial herb with white flowers. It can grow up to 6 feet tall and produce thousands of seeds per plant. In Wyoming, perennial pepperweed is a major threat to riparian ecosystems. The plant's deep root system can destabilize riverbanks and increase erosion. It also reduces water quality by shading out aquatic plants and filtering out nutrients. Wildlife also suffers as their habitat and food sources dwindle. Once established, perennial pepperweed is difficult to control. Its deep root system makes it resistant to mechanical removal, and it can quickly recover from herbicide applications.

  • This weed is known for its high salt tolerance, enabling it to thrive in saline environments
  • It is characterized by its bushy nature with many branches covered in narrow leaves

Hoary Cress

Often called whitetop, hoary cress, is a serious threat to native ecosystems. This invasive plant outcompetes native plants, reducing biodiversity and altering the land's nutrient balance. As hoary cress proliferates, native wildlife loses essential habitat and food sources. Early detection and rapid response are essential to preventing the spread of hoary cress. Landowners and managers should regularly inspect their properties for signs of hoary cress and take steps to control it immediately. Selective use of herbicides and fostering competitive native plants can help suppress hoary cress populations.

  • Hoary cress produces small, white flowers in clusters that give it a distinctive look
  • Its leaves are covered in fine, grayish-white hairs, which contribute to its "hoary" or silvery appearance

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