Tribulus terrestris

Keys to Identification

• Small yellow flowers
• Dissected leaflets
• Woody, spiny seedpods

Family

Zygophyllaceae – Caltrop Family

Other Names

Goatheads

USDA Code

TRTE

Legal Status

Colorado Noxious Weed List C

Identification

Lifecycle

Annual

Growth form

Low growing forb

Flower

Small 5-petaled yellow flowers at the leaf axils. March-October

Seeds/Fruit

Seeds are woody with two spines.  Separate into 4-5 nutlets, each with 3-5 seeds.  May remain viable for 5+ years

Leaves

Dark green, pinnately compound, opposite

Stems

1.5-5 feet long, trailing along the ground.  Slender, slightly hairy. Grow radially from a central crown

Roots

Taproot

Seedling

Seed leaves (cotyledons) are oblong, opposite, slightly hairy.  Similar to mature leaves

Similar Species

Exotics

Prostrate spurge, Prostrate knotweed

Natives

None

Impacts

Agricultural

Poisonous to sheep

Ecological

Forms large dense mats that prevent other plants from growing

Human

Seedheads may puncture bike tires.  Seedheads may attach to gear, pets, and shoes

Habitat and Distribution

General requirements

Likes sunny, dry, sandy to gravely sites.  Found in pastures, orchards, vineyards, rights-of-way, trailheads, and vacant lands

Distribution

Found throughout the continental US and parts of Canada

Historical

Originally fro Europe, Africa and Asia

Biology/Ecology

Life cycle

Annual.  Germinates throughout the season from spring until frost

Mode of reproduction

Seed.  May stay viable for 5+ years

Dispersal

Seeds attach to wildlife, pets, vehicles and equipment

References

Invasives.org – https://www.tnipc.org/invasive-plants/plant-details/?id=93

UC Davis IPM – http://ipm.ucanr.edu/PMG/WEEDS/puncturevine.html

BugwoodWiki – https://wiki.bugwood.org/HPIPM:Puncturevine