Puncturevine Identification Guide

Key Identifying Features

Puncturevine (Tribulus terrestris), also called goathead, is a low, flat, ground-hugging annual broadleaf weed infamous for woody seed burs with sharp spines that can puncture bicycle tires and bare feet. Its mat of trailing stems with small yellow flowers and ferny leaves is distinctive.

• Prostrate stems radiating flat from a central root, forming circular mats
• Pinnately compound leaves with paired oval leaflets (fern-like)
• Small five-petaled yellow flowers
• Spiny, horned seed burs ("goatheads") that resemble a goat's skull

Leaves & Stems

Leaves are opposite, pinnately compound, each with 4-8 pairs of small oval leaflets about 1/4 inch long, giving a soft, ferny appearance. Leaflets and stems are often hairy.

Stems are trailing and branching, radiating outward flat along the ground from a stout central taproot, sometimes forming mats 2-5 feet across. They rarely climb; the "vine" name refers to the spreading habit, not climbing. Stems are reddish-green and slightly hairy.

Flowers & Fruit

Flowers are small (about 1/3 to 1/2 inch wide), bright yellow, with five petals, borne singly in the leaf axils, opening in sunny weather from spring through fall. The fruit is the dangerous part: a woody bur that splits into 4-5 segments, each armed with two sharp, stout spines resembling a goat's or bull's head. These burs lie on the ground and easily lodge in tires, shoes, and feet.

How to Tell It Apart from Look-Alikes

• Sandbur: a grass with round spiny burs; puncturevine is a broadleaf with ferny leaves and two-horned burs.
• Black medic (Medicago lupulina): has yellow flowers and trifoliate leaves, but no spiny burs and clover-like leaflets in threes, not many-paired pinnate leaves.
• Spurge (Euphorbia): also prostrate, but it has milky sap, simple leaves, and no spiny burs.

The two-horned woody goathead bur plus ferny paired leaflets and yellow flowers is conclusive.

Where You'll Find It

Puncturevine thrives in hot, dry, disturbed ground: roadsides, gravel lots, sidewalk cracks, fields, trails, driveways, and waste areas. It tolerates poor compacted soil and drought, and is widespread across warm temperate regions of North America and worldwide.

Quick ID Checklist

• Flat, ground-hugging mat radiating from a central taproot
• Ferny paired leaflets (pinnately compound, hairy)
• Small bright yellow 5-petaled flowers
• Woody burs with two sharp horns (goatheads)
• Stems reddish, hairy, trailing not climbing
• Dry, hot, disturbed habitat