Spring
Volume 3, Issue 1
2012
From the Ground Up A Gardening and Native Plants Quarterly
Colorado State University Extension-Pueblo County 701 Court Street · Suite C · Pueblo, CO 81003 · 719-583-6566 · coopext_pueblo@mail.colostate.edu WICKED WEEDS
TRIBULUS TERRESTRIS, A.K.A. PUNCTUREVINE by Marcia Weaber, Colorado Master Gardener 2005, and Native Plant Master, 2007
Puncturevine, goathead, and tack-burr are common names for Tribulus terrestris, one of the most aggravating weeds in our area. It not only injures humans and pets, it will do major damage to flooring, as well as puncture bicycle tires, with its many burrs with sharp spines. Puncturevine is a prostrate, mat-forming, broadleaf summer annual with an extensive root system. Listed as a ―C-rated‖ noxious weed in many states, puncturevine produces leaves that contain compounds called saponins, which can be toxic to livestock (especially sheep) when eaten in quantity. It is prevalent in areas with hot summers and cannot tolerate freezing temperatures. In our area puncturevine is found in orchards, crop fields, roadsides, railways, walkways, lawns and other disturbed areas. It is often found in areas with high soil compaction. The cotyledons (seed leaves) are green above and grayish underneath. The first and later leaves resemble those of the mature plant. The thick, oblong cotyledons are brittle, have a slightly indented tip, and are creased Photo by Eric Coombs, Oregon Department along the prominent midvein. They are 1/6 to 3/5 of an inch long. of Agriculture, Bugwood.org The plants are described as growing ―prostrate over open ground, but when shaded or competing with other plants they can grow nearly erect. Stems occasionally grow over 3 feet long, have many branches, are green to reddish brown, and spread radially from the crown. Stems and leaves are covered with hairs. Leaves are finely divided into three to seven pairs of leaflets, and opposite to one another along the stem.‖ Puncturevine germinates in the spring and summer from seeds produced the previous year as soon as the soil temperature and soil moisture are sufficient, often by mid-May in Pueblo. The plants flower within 3 weeks of germination and flowering will continue throughout the summer. The flowers are bright yellow and are produced singly where the stem and leaf stalk meet. They open only on sunny mornings, except in shady areas. As the seedpod matures, it turns gray or tan, gets very hard and breaks apart so that the individual spikes, or burrs, can stick into passing animals and tires. These burrs disperse by adhering to tires, shoes and clothing of people, and the fur, feathers, or feet of animals. Continued on page 2
INDEX Wicked Weeds 1&2 Fabulous Families 2 Tomatoes for Lovers 3 Perennial People 4 Permaculture 5 Digging Deeper 6 Harmonious Hardscapes 7 Canning Classes 8
Gardening Myths 8&9 Summer Bulbs 9 NPM Program 10 Know Youth Natives 11 Chill Units 12 Garden Walks 13 Plant Sale 14 Interesting Insects 15 & 16