Camelthorn

Alhagi maurorum

Class A Noxious Weed

This plant is new to the state and has been designated a Class A Noxious Weed by the New Mexico Department of Agriculture.

Livestock Hazard

This plant presents a threat to the health and/or quality of livestock.
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Infrastructure Threat

This weed can cause damage to private and municipal structures. Vegetation may crack foundations and water pipes or damage roads/sidewalks.
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QUICK FACTS

Camelthorn is a thorny plant from the pea family that aggressively competes with native vegetation and crops, depleting soil nutrients and disrupting ecosystems, especially in arid regions.
It thrives in various soil types, including moist and clay-rich soils, and can spread rapidly through both seeds and its deep, extensive root system, making it difficult to control.
Camelthorn’s sharp thorns deter livestock from grazing, and its invasive nature poses significant challenges to farmers and ecosystems, including serving as a host for other invasive species like the parasitic cuscuta.

1. Overview

family	Fabaceae – legumes	origin	Middle East
life cycle	Perennial	other names	Persian manna, Caspian manna

It’s tough, it’s prickly, and it’s here to make life difficult for gardeners, farmers, and anyone who values a peaceful, weed-free existence.

Camelthorn, also known as Persian manna, is an invasive and noxious plant from the Fabaceae or pea family. It poses significant environmental and agricultural challenges in the Western regions of North America. Native to parts of the Middle East, Central Asia, and North Africa, this plant has spread widely in arid and semi-arid environments. Camelthorn has a deep root system and can thrive in harsh conditions. It aggressively competes with native vegetation and crops, depleting soil nutrients. It deters livestock from accessing healthy forage and spreads via the few animals that ingest it.

History of Camelthorn

Camelthorn is native to the Mediterranean, western Asia, and parts of Russia. It was introduced to California before 1915, primarily through Turkish alfalfa seeds brought to the area. Interestingly, it also infiltrated the United States via soil attached to date fruit seedlings, which contained camel feces that carried seeds.

By 2011, this species had been recognized as a significant weed issue in nine states throughout the western United States, indicating its ability to adapt and thrive in new environments. Currently, the United States Department of Agriculture (USDA) has identified the presence of this invasive plant in five specific counties within New Mexico, which causes concern for its impact on local ecosystems and agricultural practices. [2,4,6]

Camelthorn has played a significant role in the Middle East and Central Asia cultures for centuries. Tribes in these areas have relied on the plant for medicine and as an essential source of fodder for camels and other livestock. It is harvested for hay in late spring, ensuring a steady food supply for camels and smaller animals. In the arid regions of the Middle East, Camelthorn is a vital fuel source. It is often sown after heavy rains to help stabilize shifting sand dunes. The dried branches are also fashioned into screens, providing much-needed barriers against the scorching desert winds. [5]

2. ID Guide

What does it look like?

Camelthorn is a slender undershrub that typically reaches an impressive height of 1 to 4 feet. Its stem and leaf surface can vary considerably; some plants display a smooth texture, while others have a delicate layer of fine hairs. [1,2,4]

Having trouble identifying a weed? Contact us.

Key Features

Roots: Camelthorn has an extensive root system with a deep taproot penetrating 6-7 feet. Numerous lateral roots are rhizomatous. [3]
Leaves: The leaves of camelthorn have entire margins and measure between 0.4 and 1 inch in length and 0.12 to 0.31 inches in width. Their shape is either obovate or elliptic-oblong, often with either a smooth or slightly fuzzy appearance. The petioles are short, around 2 millimeters in length, and the stipules, while present, are minuscule. [1,2,4]
Flowers: Camelthorn has pea-like flower racemes that grow on the sides of the stems, which can be about half an inch to 2 inches long, often culminating in a sharp spine at the branch end. Each flower is supported by a slender pedicel that measures between approximately 0.04 and 0.12 inches and is usually accompanied by 1 to 2 tiny bracts. The outer part of the flower is smooth and hairless. It’s about the size of a blueberry, measuring 0.08 to 0.1 inches. It has little pointed tips that create a triangular shape. The flower petals are brightly colored, ranging from about 0.24 to 0.35 inches long. They appear in beautiful shades of pink or reddish violet. [1,2]
Seeds: The fruit of camelthorn is a pea-like pod, varying in length from 0.75 to 1.3 inches and measuring 0.08 to 0.12 inches in width. These pods have a visible constriction between the seeds, giving them an appearance that distinguishes them from other legumes. Between 1 and 9 seeds are nestled securely within each seed pod. [1,2]

Jugal Patel, inaturalist.org

The flower petals are brightly colored, ranging from about 0.24 to 0.35 inches long.

Steve Dewey, Utah State University, Bugwood.org

The thorns can puncture bike and car tires, increasing the risk of human injury.

Steve Dewey, Utah State University, Bugwood.org

Camelthorn has an extensive root system with a deep taproot penetrating 6-7 feet.

Jugal Patel, inaturalist.org

Oblong-oval leaves measure between 0.4 and 1 inch in length and 0.12 to 0.31 inches in width.

John M. Randall, The Nature Conservancy, Bugwood.org

Camelthorn typically reaches an impressive height of 1 to 4 feet.

Madeline Maher, APHIS, Bugwood.org

Seeds are capable of surviving for more than 20 years in semi-arid soils and total submersion for about eight months.

3. Infestation Basics

“Camelthorn is a hardy and aggressive species with a deep root system, which makes control and management of established populations very difficult and costly.”

–Farzad Bijani, et al, 2021 [7]

Where does it grow, and how does it spread?

This invasive weed thrives in deep soils where it will utilize all available moisture. It is commonly found in irrigation ditches, flash flood areas, fertile agricultural areas, riverbanks, and any location where its roots can access the water table. [2,3]

Camelthorn exhibits a remarkable adaptability to various soil types, flourishing even in heavy clay soils frequently encountered in New Mexico while also demonstrating a tolerance to low salinity levels. Although it prefers a moist environment, this resilient plant can endure drier or more rocky soils. [2,3]

Camelthorn can be found in US hardiness zones 3-4, particularly in desert areas. It is listed as introduced to Texas, New Mexico, Utah, Colorado, Arizona, Nevada, California, Washington, and Idaho. [6]

Key takeaway: Camelthorn is a highly adaptable plant that thrives in various soil types, including heavy clay and low salinity, and can endure dry or rocky conditions, particularly in desert regions across the West.

Why is it so invasive?

Camelthorn spreads primarily through creeping rhizomes or root crown fragments. It also stores large amounts of energy in the roots, allowing for rapid re-establishment after the rest of the plant is cut. This means that physical removal is generally unsuccessful without parallel management methods and may leave behind root fragments that will reinstitute the infestation. [8]

This aggressive weed can grow up and through asphalt pavement, posing a risk to existing infrastructure. The sharp spines add threat as they can puncture car tires, leading to further risk of injury or loss of property. Livestock may be deterred from grazing in areas with camelthorn, leading to an economic loss regarding the cattle industry. Small children or pets may be injured if camelthorn invades frequented domestic regions. [8]

Camelthorn reproduces both through seed and vegetatively through an extensive rhizomatous root system. Seeds are capable of surviving for more than 20 years in semi-arid soils and total submersion for about eight months. It is theorized that after a year in cold, wet conditions, the seed will become less viable. Seeds will germinate once they are hidden from light. The seed coat must be worn away (scarified) for germination to occur. This usually happens when the seed experiences flash flooding or is exposed to an animal’s digestive tract. [2,4]

The rhizomatous roots of camelthorn can reach depths of over 6 feet and spread to an area of more than 40 feet in diameter. Some plants have been known to access water tables up to 15 feet deep. New vegetative plants will develop deep underground, and subsequent generations will build their own root system. [4]

Key takeaway: Camelthorn spreads through rhizomes and root fragments, making physical removal ineffective while posing risks to infrastructure, livestock, and safety.

Common risk factors for invasion

Riparian Areas: Seeds are easily carried by streams and may be subsequently deposited on river terraces. While Camelthorn does not tolerate frequent flooding, being near streams or rivers allows the weed’s roots to reach the water table easily.
Deep Loam or Clay Soils: The roots of camelthorn thrive in non-rocky soils where they can quickly descend to the water table. This allows the plant to grow in arid environments without frequent rainfall and survive even the worst droughts.
Desert Environments: Usually found 100-5000 feet in elevation, camelthorn will not survive in frequently flooded areas or regions with heavy rainfall. The plant prefers dry, hot environments not subject to cold temperatures or frost.
Soil disturbance: Camelthorn loves to invade areas where soil has been disturbed, such as construction sites, tilled fields, or overgrazed pastures. This disruption weakens existing vegetation and allows the weed to become established. Minimizing unnecessary soil disturbance can help reduce the risk of invasion.

Impacts

Livestock

Camels are known to graze on camelthorn without reservation, enjoying this plant as a food source in desert climates. Other livestock steer clear of these plants, likely due to their sharp thorns. This invasive weed is incredibly hard to get rid of because it can regrow from even the smallest root fragments. As it grows, it develops rigid, sharp spines that keep livestock (excluding camels) from grazing on it, allowing it to dominate rangelands. [2,5]

Health and Safety

The plant can physically injure children, workers, livestock, and wildlife, causing puncture wounds, skin irritation, or infections. The obstruction of firebreaks and pathways by large weed infestations can exacerbate fire risks in dry regions, threatening property and personal safety.

The thorns can puncture bike and car tires, increasing the risk of human injury. [2,5]

Ecosystem Health

Once established, weed displaces native plants, resulting in a notable loss of floral and faunal biodiversity. This can significantly reduce forage availability for game, particularly during the winter months, and may even alter migratory patterns. Contributing to its obnoxious nature, camelthorn can host another invasive threat—the parasitic cuscuta species—adding another layer of difficulty to control efforts. [2,5]

Infrastructure Issues

Camelthorn can penetrate up through asphalt pavement. This unique ability allows the plant to undermine the stability of paved areas such as roads, parking lots, sidewalks, and driveways, leading to costly repairs and maintenance, particularly in the southern regions of New Mexico, where the weed is more common. [8]

4. Management Strategies

Preventing camelthorn establishment is the most important factor for managing this weed. Manual methods, such as hand pulling or digging, can help control isolated populations, but this is only practical for sparse areas. Mechanical methods like tillage can stress root reserves when repeated over multiple seasons, though they may leave root fragments that lead to regrowth. Mowing or shredding is generally ineffective as camelthorn regrows rapidly after cutting. Prescribed fire is not recommended as it leaves the root crowns intact, and flooding may help control camelthorn in certain areas with natural basins. However, its application is limited to water reserves.

DO’s

Detect and remove small camelthorn populations as soon as they are identified to prevent the spread of the weed.
Minimize soil disturbance and encourage revegetation with desirable native species to prevent camelthorn establishment.
Use an integrated management approach combining manual, mechanical, cultural, and biological controls for greater effectiveness.

DON’Ts

Use tilling as a single method-Tilling can break up the root system, leaving fragments that may lead to further infestations if not combined with other methods like chemical control.
Transport root fragments or seeds. Ensure vehicles and equipment are cleaned of soil or plant material after being in infested areas.
Overlook small infestations as early-stage camelthorn growth can lead to more widespread infestations, making control much more difficult and costly.

** The following information is provided courtesy of the UC Weed Research and Information Center. The Taos Soil and Water Conservation District does not endorse the use of any particular product, brand, or application thereof. **

Effective non-chemical control of camelthorn is difficult, as these methods are usually fruitless or unrealistically labor-intensive and/or expensive.

Mechanical (pulling, cutting, disking)

Mechanical removal is not effective, as it can stimulate remaining roots to spread and to develop new shoots.

Tillage can spread plant fragments which resprout. Tilling multiple times per season may eventually deplete an infestation over several seasons but is very expensive and impractical on rangeland and in natural areas.

When plants are less spiny, cattle and sheep can graze camelthorn. Cattle may preferentially feed on pods, but moving livestock that have browsed on fruits can disperse seeds to new locations. To avoid spread by livestock, forage should be weed-free. Restrict grazing in areas where camelthorn occurs and quarantine livestock for seven days after they have fed on the weed.

Burning is not an effective control method, as fire stimulates root sprouting.

Currently, no registered biocontrol agent for camelthorn is available in the United States.

The following specific use information is based on published papers and reports by researchers and land managers. Other trade names may be available, and other compounds also are labeled for this weed. Directions for use may vary between brands; see label before use. Herbicides are listed by mode of action and then alphabetically. The order of herbicide listing is not reflective of the order of efficacy or preference.

2,4-D

Several names

Rate: 3.2 to 4.2 qt product/acre (3 to 4 lb a.e./acre)

Timing: Postemergence to rapidly growing plants, particularly at the flower bud stage.

Remarks: Experimental results indicate effective control using 3 to 4 lb a.e./acre 2,4-D twice annually for 3 years. Repeated applications at the label rate may be effective. Do not apply ester formulations when outside temperatures exceed 80°F.

2,4-D + dicamba tank mix

Rate: 1.6 qt product/acre of 2,4-D + 1.5 qt product/acre of dicamba

Timing: Postemergence to rapidly growing plants.

Remarks: One study reported 95% control using this tank mix treatment.

Aminopyralid

Milestone

Rate: 5 to 7 oz product/acre (1.25 to 1.75 oz a.e./acre)

Timing: Postemergence to rapidly growing plants before bloom.

Remarks: Aminopyralid is a broadleaf herbicide similar to picloram, but more selective and with shorter soil residual activity. Very safe on grasses. The residual activity of aminopyralid will also provide preemergence control of germinating seeds.

Aminopyralid + triclopyr

Capstone or tank mix

Rate: 4 to 8 pt product (Capstone)/acre

Timing: Postemergence to rapidly growing plants before bloom.

Remarks: Residual activity will also provide preemergence control of germinating seeds.

Picloram

Tordon 22K

Rate: 2 to 4 pt product/acre (0.5 to 1 lb a.e./acre)

Timing: Postemergence in spring or fall.

Remarks: Picloram is one of the most effective chemical control options. It has long soil residual, so broadcast applications will also control germinating seed. Can be tank mixed with triclopyr, imazapyr, or glyphosate for improved control. Picloram is a restricted use herbicide. Not registered for use in California.

Glyphosate

Roundup, Accord XRT II, and others

Rate: 2 qt product (Roundup ProMax)/acre (2.25 lb a.e./acre)

Timing: Postemergence to rapidly growing plants. Most effective in spring or fall.

Remarks: Glyphosate has no soil activity and is nonselective. Repeated applications will probably be necessary. This species is a good candidate for wiper applications at 33% to 50% v/v solution.

Imazapyr

Arsenal, Habitat, Chopper, Stalker, Polaris

Rate: 3 to 4 pt product (Habitat)/acre (0.75 to 1 lb a.e./acre) broadcast, or spot treatment with 0.75 to

1.5 qt per 100 gal water (0.2 to 0.4% v/v solution). Chopper or Stalker can also be used in basal bark treatments at 20% v/v solution with methylated seed oil.

Timing: Postemergence to rapidly growing plants.

Remarks: Imazapyr has a fairly long soil residual and is nearly non- selective.

Metsulfuron

Escort

Rate: 1 to 3 oz product/acre (0.6 to 1.8 oz a.i./acre) broadcast, or spot treatment with 1 to 2 oz per 100 gal water.

Timing: Postemergence to rapidly growing plants at flower bud stage.

Remarks: Metsulfuron has some soil residual activity. It is safe on most grasses. Not registered for use in California.

5. Educational Video

Video for Camelthorn

This video is specific to camelthorn in Taos County and was the result of a collaboration between Taos Soil & Water Conservation District and New Mexico State University.

6. References

Citations

[1] Flora of Pakistan Vol. 0: 319 in eFloras.org, Missouri Botanical Garden. Accessed Dec 3, 2024.

[2] “Weedric Natural Areas Common A-B.” Weed Research and Information Center, UC Davis, 12 Apr. 2024, wric.ucdavis.edu/information/natural areas/natural_areas_common_A-B.htm.

[3] Washington State Noxious Weed Control Board. “Washington State.” Washington State Noxious Weed Control Board, www.nwcb.wa.gov/weeds/camelthorn. Accessed 10 Dec. 2024.

[4] Oregon Department of Agriculture. “Weeds and Weedmapper.” State of Oregon: Weeds and WeedMapper – Oregon State Weed Board, 2011, www.oregon.gov/ODA/programs/Weeds/Pages/WeedBoard.aspx.

[5] Platis, D., et al. (2023). Underutilized Vegetable Crops in the Mediterranean Region: A Literature Review of Their Requirements and the Ecosystem Services Provided: Sustainability, 15(6), 4921.

[6] USDA. “Alhagi Maurorum Medik.” USDA Plants Database, plants.usda.gov/plant-profile/ALMA12. Accessed 10 Dec. 2024.

[7] Bijani, Farzad, et al. “Impact of Aceria Alhagi as a Potential Biological Control Agent on the Invasive Weed Alhagi Maurorum in Its Native Range.” Experimental and Applied Acarology, vol. 83, no. 2, 2 Jan. 2021, pp. 229–239, https://doi.org/10.1007/s10493-020-00585-0. Accessed 24 Jan. 2025.

[8] Forest Service. Field Guide for Managing Camelthorn in the Southwest. USDA, Sept. 2014, www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410108.pdf.

twegs50, inaturalist.org

nicole_eiten, inaturalist.org

Fun Facts

In Israel and the Jordan Valley, a medicine derived from the seeds is used to treat kidney stones. The stems and leaves of this plant yield a unique sugary substance known as “manna.” This natural product is frequently found in Indian markets and sold under the name “torajabin.” In contemporary applications, manna is not only enjoyed for its traditional uses but is also processed to extract mannitol—a versatile compound used to create cosmetics, laxatives, and sweeteners. [5]