Source: Idaho's Noxious Weeds by Robert H. Callihan & Timothy W. Miller
BACKGROUND
Puncturevine (Tribulus terrestris)is a thoroughly naturalized invader from Europe. It spreads by seed and is most often found on sandy, dry, or gravely sites. Puncturevine produces sharply pointed burs that stick painfully in bare feet and cause bicycle flats, reducing the recreational potential of many areas. Even light truck tires can be punctured by seeds.
DESCRIPTION
Puncturevine is a prostrate annualPlant that germinates, flowers, seeds, and dies during one growing season that forms dense mats up to 4 feet across. Leaves are oppositeLeaves situated directly across the stem from each other and pinnatelyWith 2 rows of leaflets, like a feather compoundLeaves with 2 or more distinct leaflets with 4 to 8 pairs of ovalEgg shaped in outline, hairy, ½ inch long leafletsLeaflike structures within a compound leaf. Stems branch from the base and from leaf axilsThe angle formed between a leaf and stem and are slender and hairy. Flowers are 5 petalled, yellow, ½ inch wide, and borne singly in leaf axils from midsummer until frost. Fruits are roughly circular, splitting into 5 sections, each with 2 large, divergent spines. These tacklike burs contain up to 4 seeds.
DISTRIBUTION
Puncturevine is found throughout the U.S., except for the northern tier states from Montana to Maine.
CONTROL
Biological control agents (seed and stem boring agents) provide fair to good control of Puncturevine in Oregon, but control levels are uncertain in Idaho. Herbicides are available for control of this weed.