7 Common Weeds in Wyoming with Pictures

Weeds are plants that can’t be easily killed and interfere with the gardener’s activities and intended goals. While looking around Wyoming gardens, backyards, rangelands, fields, and pastures, you will find several unwanted plants.

Some of the most common weeds are eatable and nutritious. However, many plants introduced from another place or native to Wyoming are harmful to humans and livestock.

In fact, Wyoming is known to have some of the most poisonous North American weeds, like poison hemlock.

So it’s essential to identify the weed species germinating in your garden correctly. And this article endeavors to unveil some of the most common weeds in Wyoming.

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Most Common Weeds in Wyoming Gardens

Have a look at the common Wyoming weeds that might be budding in your well-manicured garden. Although they can be edible or poisonous, get rid of them without aforethought.

Keep in mind that weeds disrupt a yard’s look and compete with other desirable plants for nutrients, water & more. It can hamper your intended harvest.

1. Canada Thistle

Canada Thistle
TypePerennial weed
Common NamesCreeping thistle, Californian thistle, Field thistle

This perennial weed grows aggressively with a vigorous root system, continually intruding on new bare areas and producing new shoots. They outcompete the surrounding vegetation types typically by secreting chemicals from the poisonous roots to other plants in that areas.

Canada thistles have the ability to drain nutrients from the soil, posing significant damage to crops and pastures. However, this weed can reproduce by root generation and seed. In addition, its extensive root system stores food energy that helps the weed to thrive in winter.

Canada thistles grow from one to five feet in height with many branches. It exhibits alternate, lance-shaped leaves, also irregularly lobed. And they have toothed/spiny margins. 

This weed usually has smooth stems, slightly grooved, and sometimes short hairs. Moreover, pink and purple flowers bloom in clusters from the end of the stems between July and August. On the other hand, seedlings crop up as small rosettes during the fall or early spring.

However, this weed species is easily recognized when flowers turn to seedheads with white wooly tops that can spread to new places.

You can control Canada thistles by pre-harvest application of glyphosate on them. This technique is more commonly used as it’s known to be twice as effective as applications done after harvest. 

On the contrary, you can snip off the weeds at ground level using household scissors. If you pull this plant, a weeding tool will be handy to remove selective plants. 

Another way to yield good results is by spraying a premium herbicide. But, fascinatingly, you can also control Canadian thistle naturally by using vinegar. Plus, if you add salt to it, the weed can die off within a few hours.

2. Black Henbane

Black Henbane
TypeAnnual or biennial weed
Common NamesHenbane, Hog’s-bean, Stinking Nightshade, White Henbane, Devil’s eyes

Another weed commonly seen in fence rows and pastures is black henbane. This weed produces continuous litter that impacts the germination and growth of desirable plants. However, every part of black henbane is highly toxic due to scopolamine, hyoscyamine, and alkaloids.

They can be highly fatal to humans and all livestock if consumed even at low doses. Nevertheless, black henbane thrives in disturbed soils. And their fine seeds can spread well in muddy tools.

Be cautious; if your bare skin touches this plant, it can cause skin irritation. So it’s important to identify this weed species –

  • Black henbane features shallowly lobed, heavy scented, and alternate leaves that are usually 6 inches wide and 8 inches long. 
  • They display greenish-yellow, tubular flowers with purple veins. Moreover, they are five-lobed and captivating, measuring up to 2-inch across. And finally, you will find flowers budding from the leaf axils on spikes.
  • You will see urn-shaped fruits with a thickened lid emerging from the calyx. However, the lid pops off when the fruit matures, leaking its black seeds.
  • Black henbane stems are hairy and coarse.

The most effective way to control this weed is by stopping its spread and germination. To ensure it, you should keep these factors in mind, like limiting seed dispersal, reducing soil disturbances, and eliminating new plants.

In addition, maintaining advantageous competitive plants can also efficiently decrease the formation and spread of this weed. Finally, herbicide spot treatment and hand pulling will help to control small-scale seed production.

Digging or pulling small infestations or isolated plants can also be effective if you remove the entire taproot. However, if you choose to pull, wear protective clothing and gloves to prevent skin irritation.

You can apply herbicides with a non-iconic surfactant before flowering and at the rosette stage. This will prevent the weed from producing seeds. Retreat if you see regrowth.

3. Common Burdock

Common Burdock
TypeBiennial weed
Common NamesBurdock, Clotbur, Burs, Wild burdock, petite bardane, rapace, bardane mineure, toques and rhubarbe sauvage.

This biennial weed reproduces by seed. Seedlings crop up in early spring, creating a big rosette during the first year. However, the rosette generates a flower stalk in the second year, extending fully by the end of June.

Well, the flat rosette leaves can dusk desirable plants in lawns and pastures. Common burdock can interfere with your intended harvest if not controlled immediately.

Common burdock seedlings have light green, fleshy and smooth cotyledons. However, they have erect, branched, thick, and coarse stems, nearly 2m tall. In the first year, the leaves create a basal rosette, and when they mature, leaves turn dark green, alternate, and triangular.

Moreover, you will find shallowly toothed and coarsely leaf margins. Hooked spines and bracts surround the tubular florets. On top, the flowers exhibit purple heads, about 1-1.5cm in thickness, at the axils of upper leaves and ends of branches.

You won’t find any biological control agents out there for common burdock. However, the best part is that you can control this weed’s growth with minimal tillage. Mow your garden as soon as the flower stalks appear. Don’t wait for the weed flowers to bud, as they will produce seeds.

You can successfully control the plant’s growth by applying several herbicides like 2 and 4-D to active rosettes during spring.

Also Read: Weeds in NC | Spot 6 Common Weeds With Pictures

4. Spotted Knapweed

Spotted Knapweed
TypeBiennial to short-lived perennial weed
Common NamesBushy Knapweed

Spotted Knapweed is a serious nemesis of lawn owners in Wyoming. This weed is categorized from a short-lived perennial to a bushy biennial, backed by a strong and long taproot. But, most importantly, these weed species are toxic, posing a serious threat to Wyoming gardeners.

At first, basal rosettes appear in the winter and early spring. Then it develops branched flowering and erect stems from late spring through summer.

Spotted Knapweed grows up to 2 to 4 feet in height. Besides its deep taproot, the plant has gray-green foliage. You will see some vertical, rough stems branching towards its upper half.

Leaves are grayish green or pale and have short hairs. However, basal leaves usually persist for four years, forming a rosette. Leaflets are irregularly lobed and tapered at either end.

Several solitary and pink-purple flowers emerge at the end of every stem between July and September. But on the other hand, this weed produces small brown seeds throughout the growing season that can be easily distributed by wind. And the seeds stay active for nearly nine years.

Start putting your efforts into the highest quality areas. You can dig or pull in small infestations and eradicate the entire root. However, be sure to wear protective clothing and gloves to prevent skin contact and, eventually, skin irritation.

Also, pick up flower or seed heads from the ground. One of the best defenses against spotted Knapweed is foliar herbicide application before the stem grows. You may need to apply multiple treatments until the seed bank exhausts.

You have to make every effort to eradicate the entire taproot system. However, maintaining a healthy lawn without overgrazing will significantly control spotted knapweed germination and spread.

5. Houndstongue

TypeBiennial weed
Common NamesGypsy flower, Dog bur, Rats, and mice

Another strong competitor of desirable fodder in Wyoming is houndstongue. This perennial weed is poisonous, containing pyrrolizidine alkaloids harmful to all livestock. Houndstongue tolerates shady areas and wetter grasslands.

This self-pollinating weed reproduces by seed. Every plant can produce between 300 to 2,000+ seeds that stay viable on the soil surface for two to three years.

Houndstongue emerges as a rosette in the first year. Stems can reach up to 1 to 4 feet in height. However, the weed is characterized by a black, woody, and thick taproot. And every part has hair. Flowers form in clusters at the upper half of the stem.

Their colors range from burgundy to a dull reddish-purple. Moreover, the flowers are five-lobed and measure about 1/4 inches in width. Flowers consist of four nutlets – each of them contains one seed.

Houndstongue has rough and hairy leaves, and the lower ones have leaf stalks. It is said while they resemble a hound’s tongue, the weed is named after it. Nevertheless, upper leaves don’t have petioles. Instead, the weed manifests vertical, coarse, and hairy stems.

Houndstongue seeds get stuck to animals, people, equipment, and more. So attempt to dust seeds before you leave a weedy site. Also, this weed should not get into hay as it can poison livestock.

Well, you can pull our dig out the entire root system. Be attentive to seedlings and resprouts! It’s necessary to control houndstongue’s expansion before seeds are produced. However, cut or mow the flowering plants to the base and eliminate them properly. It will help decrease seed production.

Finally, replaying young rosettes and re-seeding affected areas with competitive plants will offer efficient control.

You May Also Read: 10 Common Weeds Found in New Hampshire (Identify them with pictures)

6. Redroot Pigweed

Redroot Pigweed
Type Annual broad-leaf
Common NamesRedroot amaranth, Rough pigweed, and Careless weed

Rough pigweed germinates in gardens and cultivated fields, tolerating dry to moist conditions. They regenerate from seeds every year. However, seeds can germinate anytime if the soil has adequate moisture. 

Some say that this weed is named ‘pigweed’ after its use as forage for pigs. On the contrary, others believe that the plant got its name from its unique red taproot.

Nevertheless, redroot pigweed is an aggressive and competitive weed in various row crops, causing substantial yield loss. So get rid of them as soon as you see this invader in your garden.

Redroot pigweed is typically 3-4 inches tall and can grow taller. Leaves feature prominent veins, ranging from oval to round in shape. However, you will find fine hairs on leaves and stems. Young leaves have a purplish undertone. 

The same plant produces male and female flowers in terminal spikes comprising short branches. You can even find additional clusters of flowers in the upper leaves. Lastly, the characterizing pigweed’s taproot can reach up to 3.9 to 95-inch in depth.

Pigweed’s seedlings are small and brittle. So you can stir the weed’s top 1-2 inches about 3 to 4 times during the first month, followed by tillage. This technique effectively eliminates the new plants that sprout during the season.

A pre-emergence herbicide application can be the best defense against this spiny pigweed as it contains the active ingredient trifluralin.

Also Read: 13 Common Weeds in Georgia | Guide to Identify With Pictures

7. Musk Thistle

Musk Thistle
Common NamesNodding thistle, Nodding plumeless thistle

Musk thistle is a biennial weed, occasionally annual, that grows aggressively in pastures, gardens, and other areas. Interestingly, this weed reproduces only by seed. And thus, the key to successfully controlling this weed is preventing seed production. 

Seeds sprout more and develop into plants in degraded or unhealthy lawns. However, this weed can also intrude on gardens or lawns in good condition.

Musk thistle appears as a basal rosette 2ft wide during the first year. Leaves are deeply lobed, displaying spine-tipped margins. The following year flower stalk generates up to 5ft in height. You will also find many purple to pink flower heads 2-inch wide.

However, the key identification traits include silverish leave margins that offer them a frosted appearance. The leaf base extends to the stem creating spiny wings on flowering plants. Moreover, leaves have few hairs.

You will commonly see this plant with heads in different stages of floral development. Eventually, this weed sets seed over a longer period.

Maintaining your lawn in good condition is the primary thing to follow for musk thistle management. You have to stop seed formation from controlling this weed successfully.

This plant can’t tolerate tillage, and you can easily remove it by cutting off the weed’s root beneath the ground using a hoe or shovel. However, mowing can yield effective results if you sever the plant in the late-flowering stage.

Several herbicides are also available to control musk thistle. Apply them during the spring or fall to yield good output. 


Maintaining and reinstating land health is among Wyoming’s highest priorities. However, invasive weeds are among lawn owners’ main obstacles and anxiety. Weeds can disrupt the aboriginal plant composition and productivity, along with ruining the look of a beautiful garden.

Thus, addressing these intruders immediately is important before they can affect your intended harvest. And remember, many weeds are noxious and can cause skin irritation if they touch your bare skin. So take proper precautions before getting into the field to deal with the invaders.

About Jennifer Igra

Growing up in Brooklyn, New York City known for it’s green gardens. Jennifer, a 30 year old gardener and green living fanatic started Igra World to share her gardening journey and increase gardening awareness among masses. Follow Igra World to improve your gardening skills.

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