Puncturevine (Tribulus terrestris)

Common Names: Mexican sandbur, Texas sandbur, bullhead, caltrop, goathead

Description: Introduced to North America from the Mediterranean in the wool of sheep imported around 1900. This species is listed under Regulation No. 715 - Seed Law Implementation as a prohibited noxious weed by the Michigan Department of Agriculture.

Habit: Forms dense mats close to the ground.

Leaves: Opposite, even-pinnate, 1.5-5 cm. long with 6-16 leaflets. Leaflets are oblong, 5-10 by 2-5 mm., slightly oblique base, entire margins and rounded tips.

Stems: Greenish-red in color, up to 2 m long with branches growing 20-60 cm. long. Can be smooth, finely hairy or covered with coarse firm hairs. Generally prostate but become erect in shade or in competition with other plants.

Flowers: Yellow in color, 5 petalled, 7-15 mm. in diameter and borne singly on a short stalks in the axils of the smaller of each pair of leaves. Open in the morning and close and shed their petals in the afternoon.

Fruit and seeds: 1 cm in diameter when mature and split into 4 or 5 segments containing 1-4 seeds each. Seeds are yellow, more or less oval and 2-5 mm. long.

Habitat: Native to Europe. Can be found in orchards, pastures, along roadsides, ditches, and almost any other type of dry, loose, sandy soils and dunes.

Reproduction: Reproduces only by seed.

Monitoring and rapid response: Small infestations can effectively be controlled by hand pulling or digging before flowering and seed production. Herbicides are suited for medium-large infestations and in agricultural areas, infestations can be tilled before seed production.

Credits: The information provided in this factsheet was gathered from the Regional District Okanagan-Similkameen and the Alberta Invasive Species Council.

Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org). Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).

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