Know your enemy
What are goat heads?
In short: goat head, puncturevine and caltrop are common names for one plant, Tribulus terrestris. It is a low, spreading summer weed of dry, disturbed ground. Its seed pods are hard burs, roughly 3 to 5 mm, with spines sharp enough to puncture bike tires, pet paws and bare feet. The seeds inside can stay viable in soil for years.
One plant, many names
Depending on where you live, you may hear goat head, goathead, puncturevine, caltrop, bullhead, cat-head, or tackweed. In Australia the same plant is often called cat's head or bindii. Botanically it is all Tribulus terrestris, and everything on this page applies regardless of the name.
How to identify it, stage by stage
The sprout
A low, flat mat of small paired leaflets, hugging the ground. It shows up in bare soil, gravel, driveways, paths and fence lines, usually after warm weather sets in. At this stage it pulls out easily, taproot and all.
The flower
Small, bright yellow, five petals, sitting close to the mat. Flowers mean the clock is ticking: each one becomes a seed pod cluster within weeks. Pull the plant now, before the pods harden.
The bur
The mature pod splits into hard segments, each with two sharp spines: the classic goat head shape. The burs detach, drop, and wait. This is the stage that punctures tires and paws, and the stage THORNADO is designed to collect.
The seed cycle, and where THORNADO fits
Left unmanaged, goat heads run a self-renewing loop. Breaking it means acting at more than one point, season after season.
- SproutA low mat of leaves in bare, dry ground.
- FlowerSmall yellow flowers set seed.
- BurSpiny seed pods harden, then detach.
- THORNADO collects hereBurs on the groundDropped burs and their seeds bank in the soil.
Seeds can stay viable in the soil for years. Left alone, a new sprout starts the cycle again. That is why control takes more than one season.
Where it grows
Goat heads thrive where most plants give up: compacted dirt, gravel, sand, roadsides, arena edges, vacant lots and the dry margins of yards. Lush, dense, irrigated lawn is not their favorite terrain. If your problem area is a gravel drive or a bare-dirt dog run in a dry region, you are squarely in puncturevine country.
Goat heads or sandburs?
People use "stickers" for both, but they are different plants. Sandburs (Cenchrus species) are grasses whose burs cling to socks and fur and feel bristly. Goat heads are broadleaf plants whose rigid, horned burs lie on the ground pointing upward, built to puncture rather than to cling. THORNADO targets goat heads: we make no claims about sandburs.
Why the thorns matter
A goat head bur is hard enough to push through a bike tube, a thin shoe sole and the pad of a paw. Because the burs drop by the hundreds and stay put, an infested path stays dangerous long after the plants themselves have died. That is why collection, not just plant removal, is half the battle.
What to do about them
The full playbook lives in our guide,how to get rid of goat heads, and the timing lives in the Goat Head Control Calendar. The short version: pull young plants before they seed, never mow an infested area, collect the dropped burs, and repeat each season.