Foxtail weed seed

Weed of the Month: the foxtails, similar yet different

Figure 1. The seed heads of giant (top), green (lower left), and yellow (lower right) foxtails. The giant foxtail seed head drops while the seed heads of the green and yellow.

The three most common foxtails in Missouri are yellow, green, and giant foxtail. These grasses, which invade fields of row crops and pastures across the U.S., begin germinating in late spring to early summer, and have many similar characteristics. All 3 have fibrous root systems, reproduce by seed, and form that distinctive, fuzzy, foxtail seed head (Figure 1). Each tends to grow upright and has a ligule that is a fringe of hairs at the junction where the leaf blade meets the stem (Figure 2). These properties can help distinguish the foxtails from many other common grassy weeds, which may have no ligules present or have ligules that are membranous with no hair. And, while the 3 foxtails can be challenging to differentiate from one another, they each have unique properties that can aid in foxtail identification.

Figure 3. Yellow foxtail is easily distinguished from giant and green foxtail by the presence of long, cobweb-like hairs in the collar region.

Figure 2. A ligule is a thin membranous sheath that occurs at the junction between the leaf and stem. The foxtails all have a ligule that is hair-like.

One of the most distinguishing features of the foxtails is the color and size of the fuzzy foxtail seed heads (Figure 1). Yellow foxtail has a compact seed head with soft, yellow bristles (or awns) while the seed head on green foxtail is usually green or purple-tinted. Giant foxtail seed heads are also greenish in color, but are usually larger, about 3 to 8 inches long, and the seed heads of giant foxtail also droop in an arch shape unlike the more erect seed heads of green and yellow foxtail.

Knowing the differences between the seed heads is useful, if the seed heads have already formed. But what about the earlier growth stages? There are a few key, but subtle, features that you can look for when identifying foxtails prior to seed head formation.

Figure 4. Foxtail seedlings, like the one pictured, are emerging in fields throughout Missouri.

The leaves also help to differentiate the foxtail species. Giant foxtail tends to have wider leaves (~3/8 to 5/8 inch) and dense hair growing on the upper surfaces of the leaves. Both green and yellow foxtail have narrower leaf blades (~1/8 to 3/8 inch wide). Green foxtail has a smooth upper leaf surface with no hairs, while yellow foxtail has sparse hairs on the upper leaf surface. These hairs grow up to 3/8” long, are light yellow/white and cobweb-like, and are located near the base where the leaf meets the stem (Figure 3).

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In addition to the leaves, the leaf sheaths, or stems, are also different. Yellow foxtail has flat leaf sheaths with a reddish tint at the base. Green foxtail and giant foxtail both have round leaf sheaths. The leaf sheath of green foxtail is usually lined with small hairs while that of giant foxtail is smooth.

For information on herbicides that provide effective control of the foxtails, purchase or download a copy of M171, the Missouri Pest Management Guide:

And for more information on the identification of foxtails and other grass weeds in Missouri, purchase or download a copy of:

Weed Seed: Setaria faberi (Giant foxtail)

Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.


Worldwide: Native to temperate eastern Asia and introduced in North America, central Europe, Russia and the Middle East (Nurse et al. 2009 Footnote 2 , USDA -ARS 2016 Footnote 3 ). In the United States, it occurs mostly in the east and is expanding westward (Nurse et al. 2009 Footnote 2 ).

Duration of life cycle

Seed or fruit type

Identification features

  • Spikelet length: 2.5 – 3.5mm
  • Spikelet width: 1.5 – 2.0 mm


  • Spikelet ovate with a pointed tip; one side is flat (plano-convex)

Surface Texture

  • Lemma surface is transversely ridged, smooth at the tip
  • Palea is grid-patterned with 2 shiny crescents along the outer edges


  • Spikelet straw yellow to medium brown

Other Features

  • The papery second glume extends up to 3/4 of the length of the lemma

Habitat and Crop Association

Cultivated fields, old fields, gardens, roadsides, railway lines and disturbed areas (Darbyshire 2003 Footnote 4 ). A weed of a variety of crops, but causes the greatest losses in corn and soybeans (Nurse et al. 2009 Footnote 2 , CABI 2016 Footnote 5 ).

General Information

Giant foxtail may have been introduced into North America as a contaminant of imported millet. It may also contaminate bird seed and flower seed mixtures as well as other crop seeds. In Canada, the occurrence of giant foxtail coincided with the cultivation of field corn beginning in the 1960s (Nurse 2009 Footnote 2 ).

Similar species

Yellow foxtail (Setaria pumila subsp. pumila)

  • Yellow foxtail is similar in size, yellow colour, lemma wrinkling and ovate shape as giant foxtail spikelets. The lemma ridges of yellow foxtail remain strong to the tip, the palea lacks the shiny outer edges of giant foxtail, and the second glume reaches halfway up the lemma.


Giant foxtail (Setaria faberi) spikelet and florets Giant foxtail (Setaria faberi) spikelet Giant foxtail (Setaria faberi) floret, lemma view Giant foxtail (Setaria faberi) floret, side view Giant foxtail (Setaria faberi) floret, palea view Giant foxtail (Setaria faberi) spikelets

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Similar species


Brouillet, L., Coursol, F., Favreau, M. and Anions, M. 2016. VASCAN, the database vascular plants of Canada, [2016, May 30].

Nurse, R. E., Darbyshire, S. J., Bertin, C. and DiTommaso, A. 2009. The Biology of Canadian Weeds. 141. Setaria faberi Herrm. Canadian Journal of Plant Science 89: 379-404.

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds. Agriculture and Agri-Food Canada, Research Branch. Ottawa, ON.

Foxtail Plants: How to Find Them on Dogs and Why They’re So Dangerous

Foxtail plants are a weed-type grass that can cause serious problems for dogs.

Flourishing in the summer months, the seeds from these annoying weeds are designed to burrow into the ground. If they attach to your pet’s coat and burrow into the skin, this can lead to pain, infection, and sometimes more serious issues. Foxtails can also be inhaled, lodged in the ears, swallowed, and embedded in the paws.

Luckily, there are things you can do to try to keep your dog safe from the dangers of foxtails. Here’s a breakdown of what the foxtail plant is and why it’s dangerous for your dog.

What Is a Foxtail? What Do Foxtails Look Like?

Foxtails—also called grass seed awns, mean seeds, timothy, cheatgrass, June grass, Downy Brome, or other local names—are an annual summer grass. They start growing in spring and are in full bloom by summer. They will then die during the winter.

Shaped like the tail of a fox, the tip has seeds arranged in spikey clusters with backward-facing barbs. 1 The spikes and barbs allow for one-way burrowing, which is great news for the foxtail but bad news for dogs.

Here are some pictures of a foxtail plant:

Here are pictures of the dangerous foxtail awns:

Shown: Common wheat grass awns / Image credit: Smith Veterinary Hospital

Shown: Brittle grass awn breaking into smaller pieces / Image credit:

Where Are Foxtails Found?

Foxtails can be found anywhere in the United States but are most common in the West. They are most often found in these places:

Open grassy fields

While they are less common in urban areas, they can still be found in areas where grass is allowed to grow uncontrolled.

When the weather is warm, the foxtail dries out and hitches a ride on anything passing by, including dogs. This hitchhiking behavior is important for foxtail seed dispersal. 1

Why Are Foxtails Dangerous for Dogs?

Foxtails can attach to any part of your dog’s body and start the burrowing process. This commonly includes: 2

Spaces between the toes (in the paw pads)

In some cases, foxtails can burrow through the skin, finding their way into the spine or chest and belly cavities. Once inside, the foxtail continues to burrow, bringing bacteria and dirt along with it.

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This can lead to much more serious conditions because internal organs may be affected. The foxtail will continue to cause problems until it is removed.

In some cases, advanced diagnostic tests and procedures may be required to identify and remove the foxtail.

What Are the Signs That a Dog Has Foxtails on Them?

If you live in an area where foxtails are abundant, here are some signs you can look for:

Pawing at the face

Excessive licking of an area on the body

Other signs can show up one to several days later. These may include:

Areas of redness or tenderness

In the worst case scenarios, an embedded foxtail can make it to vital organs, including the lungs, spinal cord or brain, heart, and abdominal organs, causing symptoms specific to that organ. In very bad cases, surgery may be required to remove foxtails or treat infection resulting from embedded foxtails.

How to Remove Foxtails From a Dog

Early removal of the foxtail is important. If you live in a foxtail-prone area, ALWAYS check your dog after being outside.

If you see a foxtail on your dog’s fur or skin, you can attempt to remove it with tweezers.

If you are seeing any of the signs listed above or signs that a foxtail has penetrated the skin or entered an opening on your dog’s body, bring your dog to the vet. This includes the ears, nose, or mouth.

Trying to remove the foxtail yourself from a body cavity may result in an incomplete removal, with pieces of the foxtail still embedded in your dog’s skin and ready to burrow deeper. Foxtails can travel a great distance through body cavities, so it’s important that the full foxtail is removed.

How to Prevent Foxtails From Injuring Your Dog

There are a few ways you can avoid foxtails and keep your dog safe.

Dogs with long coats are more likely to pick up these annoying hitchhikers. Consider a trim for the summer to reduce the likelihood of attachment.

Working dogs, or dogs that spend a lot of time in tall grass, may be outfitted with a commercially available vest that covers and protects the chest and abdomen.

Avoid foxtail-prone areas to prevent injury to your dog.

Use a short leash when walking your dog.

If foxtails grow in your yard, make plans to remove them or call a landscaper for assistance.

Check for foxtails frequently and after periods of outdoor play, especially if you hike or spend time in foxtail-prone areas.

Foxtail (diaspore). (2019, June 2). In Wikipedia. Retrieved from

Brennan KE, Ihrke PJ. Grass awn migration in dogs and cats: A retrospective study of 182 cases. Am Vet Med Assoc. 1983.182(11):1201-1204