Puncturevine [Tribulus terrestris L.][TRBTE][CDFA list: C] Photographs

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SYNONYMS:caltrop, tackweed, ground burnut, puncture weed, bullhead, goathead, Mexican sandbur

GENERAL DESCRIPTION:Noxious summer annual, with prostrate stems up to 2.4 m long. Plants produce many stout-spined burrs that can injure people and animals and puncture bicycle tires. Foliage is toxic to livestock, especially sheep, when consumed in quantity. Fruits are used medicinally in India. Introduced from the Mediterranean region. Once one of California’s most troublesome weeds, puncturevine is currently controlled by the stem weevil (Microlarinus lypriformis) and seed weevil (M. lareynii), introduced from Italy as biocontrol agents in 1961.

SEEDLINGS:Mature rapidly. Cotyledons oblong, 4-15 mm long, thick, creased down the center, slightly indented at the tips. First and subsequent leaves resemble those of mature plants.

MATURE PLANT:Stems highly branched, green to reddish-brown, prostrate and spreading radially from the crown on open ground to +/- erect when shaded or competing with other plants. Foliage often sparse to moderately covered with silky and/or bristly silver hairs. Leaves opposite, even-pinnate compound, ~ 3-5 cm long, with 3-7 leaflet pairs per leaf and a small extension at the tip. Leaflets oblong, 5-15 mm long, with +/- oblique bases. Stipules leaf-like. Photosynthesis is by the C4 pathway.

ROOTS and UNDERGROUND STRUCTURES:Taproot deep (to 2.6 m), slender, branched, often somewhat woody, with a network of numerous fine rootlets. Roots can develop nitrogen-fixing nodules.

FLOWERS:April-October. Flowers axillary, solitary, bright yellow, 5-15 mm in diameter. Petals and sepals 5(4), deciduous. Stamens and ovary chambers twice the number of petals. Insect-pollinated.

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FRUITS and SEEDS:Woody burrs gray to yellowish-tan, hairy, to ~ 1 cm in diameter, +/- flattened, lobed, separate into 5(4) wedge-shaped nutlets, each with 2 stout spines 4-7 mm long and several prickles. Seeds usually 3-5 per nutlet, remain enclosed within burrs.

POSTSENESCENCE CHARACTERISTICS:Burrs often remain on senesced plants or the soil surface.

HABITAT:Disturbed places, roadsides, railways, cultivated fields, yards, waste places, walk ways. Grows best on dry sandy soils, but tolerates most soil types. Intolerant of freezing temperatures.

DISTRIBUTION:Throughout California, to 1000 m (3300 ft); to Wyoming, Eastern U.S., Central Mexico. Nearly worldwide. Prevalent in areas with hot summers and dry soils.

PROPAGATION/PHENOLOGY:Reproduces by seed. Nutlets disperse by adhering to tires, shoes and clothing of people, fur, feathers, and feet of animals. Most newly matured seeds are dormant and require an afterripening period of ~ 6 months to 1 year. Germination requires warm temperatures. The largest seed in a nutlet is usually the first to germinate. Other seeds may germinate or remain dormant depending on moisture availability. Buried seed can remain viable for several years. Seedlings emerge early spring through summer, often in flushes following increased soil moisture. On sandy soils, seedlings emerge from depths to ~ 5 cm (less on heavy soils). Seedlings develop a deep root system in a few weeks, and flowers may be produced within 3 weeks, burrs within 6 weeks. Plants typically bear numerous burrs (average 200-5000) until the cool season commences. In tropical regions, plants develop woody roots and become perennial.

MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:Removal of plants with burrs and repeated cultivation to prevent burr formation or planting competitive vegetation can help control infestations.

SIMILAR SPECIES:Puncturevine is unlikely to be confused with other weeds.


Mechanical: Tillage following germination and emergence is effective. However, tillage may bury seed that remain viable in the soil for several years. Hand-pulling is feasible for small infestations and is easiest when soils are moist and the vines are long enough to grasp. Mowing is ineffective due to the prostrate growth habit of the plant.
Biological: There are two species of weevils which are being used to control puncturevine. The stem boring weevil, Microlarinus lareynii and the fruit boring weevil Microlarinus lypriformis. The insect larvae attack the seeds and stems and have given good puncturevine control. Both insects are available in California for release.
Chemical: Chlorosulfuron, 2,4-D, imazapyr, MCPA, paraquat, glyphosate, and dicamba are effective on puncturevine. Consult the label for proper rate and timing.

Johnson, E. 1932. The puncturevine in California. Univ. of Calif. Agric. Expt. Sta. Bull. 528: 42 pp.
Parsons WT and Cuthbertson EG (1992). Noxious Weeds of Australia. Inkata Press, Melbourne, Australia..
Squires, V.R. 1979. The biology of Australian weeds. 1. Tribulus terrestris L. J. of the Australian Inst. of Agric. Sci. 179: 75-82.

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