Noxious weed with flat two barbed seed

Seeds That Stick To Clothing: Different Types Of Hitchhiker Plants

Even now, they’re lingering along the roadside waiting for you to pick them up and take them wherever you’re going. Some will ride inside your car, others on the chassis and a few lucky ones will find their way into your clothing. Yes, weeds that spread by people, or hitchhiking, have certainly taken advantage of you this year. In fact, the average car carries two to four seeds for hitchhiker plants at any given time!

What are Hitchhiker Weeds?

Weed seeds spread in a variety of ways, whether traveling by water, by air, or on animals. The group of weeds nicknamed the “hitchhikers” are seeds that stick to clothing and fur, making it difficult to dislodge them immediately. Their variously barbed adaptations ensure that the seeds will travel far and wide via animal locomotion, and most can be eventually shaken off down the road somewhere.

Although it might sound like all fun and games, the weeds spread by people are not only difficult to contain, they’re costly for everyone. Farmers lose an estimated $7.4 billion each year in productivity to eradicate these pest plants. Humans are spreading these seeds at a rate of 500 million to one billion seeds a year in cars alone!

Although the weeds within crop stands are annoying, those that appear in fields can be downright dangerous for grazing animals like horses and cattle.

Types of Hitchhiker Plants

There are at least 600 weed species that travel by hitchhiking with humans or on machines, 248 of which are considered noxious or invasive plants in North America. They come from every kind of plant, from herbaceous annuals to woody shrubs, and occupy every corner of the world. A few plants you might be familiar with include the following:

  • “Stick-tight” Harpagonella (Harpagonella palmeri)
  • “Beggerticks” (Bidens) (Krameria grayi) (Tribulus terrestris) (Opuntia bigelovii) (Torilis arvensis) (Symphyotrichum lateriflorum) (Arctium minus) (Cynoglossum officinale) (Cenchrus)

You can help slow the spread of these hitchhikers by carefully inspecting your clothing and pets before emerging from a wild area full of seeding plants, making sure to leave those unwanted weeds behind. Also, reseeding disturbed areas like your garden plot with a cover crop can ensure that there’s too much competition for hitchhikers to thrive.

Once those weeds emerge, digging them out is the only cure. Make sure to get three to four inches (7.5 to 10 cm.) of root when the plant is young, or else it’ll grow back from root fragments. If your problem plant is already flowering or going to seed, you can clip it at the ground and carefully bag it for disposal – composting will not destroy many of these types of weeds.

Last, but not least, check your car any time you’ve been driving on unpaved roads or through muddy areas. Even if you don’t see any weed seeds, it wouldn’t hurt to clean your wheel wells, undercarriage and any other location where seeds might be hitching a ride.

Noxious weed with flat two barbed seed

Mostly erect, winter (cool-season) annual grass closely related to and resembling winter wheat, 5-1/2 to 19-1/2 inches tall, with a tufted appearance; roots are fibrous; reproduces by seed.

Plants: Culms erect, branching at the base, spreading, or abruptly bent near the base; blades flat, 1-1/8 to 6 inches long and about 1/16 to 3/16 inch wide; lower surface and sometimes upper surface sparsely covered with fine hairs; sheaths open; ligule membranous, less than 1/16 inch long, with the upper margins finely fringed; auricles about 1/16 inch long, ciliate, with hairs less than 1/8 inch long.

Inflorescence/Spikelet/Floret: Flowers May to June; inflorescence is a narrow, cylindrical spike 7/8 to 4-3/4 inches long, disperses as a unit at maturity, but ultimately breaks apart into joints; joints cylindrical, with blunt ends; spikelets 1 per node, 3/8 to 1/2 inch long, alternate, laying flat against and fitting into a groove in a zig-zag rachis; 2 to 5 florets/spikelet, the lower 2 usually fertile; glumes 1/4 to 3/8 inch long, mostly 6 to 9 nerves, awned, awns of lower glumes acute or tapered, less than 3/4 inch long, awns of upper glumes 1-3/16 to 3-1/8 inches long; lemmas about 3/8 inch long, 5 to 7 nerves, awns of lower lemmas about 3/4 inch long, awns of the upper lemmas 1-3/16 to 2-3/4 inches long; awns of both glume and lemma awns are flanked by two teeth as well as being stiff, sharp, and minutely barbed; caryopses about 1/4 inch long, oblong, reddish to light brown, grooved, with short hairs at the apex, and adhering to the lemma and palea.


Cultivated and disturbed or degraded dry sites in grassland and woodland communities, and roadsides within elevations that generally range from 5,300 to 7,000 feet.


Reproduces by seed; one plant produces about 130 seeds, but isolated plants can produce as many as 3,000 seeds; some seeds can remain dormant for 2 or more years.


Native to the Mediterranean region and central Asia; jointed goatgrass can hybridize with winter wheat. Arizona prohibited/restricted noxious weed and New Mexico Class C noxious weed.

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