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Willow Lake - Sue Smith

Yavapai County Native & Naturalized Plants

Tribulus terrestris - puncturevine

Other Common Names: goat's head, puncture-weed, ground bur-nut, tackweed, torrito, bull-head
Plant Form: Forb or Subshrub

Family: Zygophyllaceae

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Granite Mtn - Tr 308
Sue Smith
Willow Lake
Sue Smith
Plant - summer
Granite Mtn - Tr 308
Sue Smith
Plant - summer
Willow Lake
Sue Smith
Granite Mtn - Tr 308
Sue Smith
Forb Plant Description

Origin: Introduced   Life Cycle: Annual
General Desc: Prostrate plant trails up to 2-1/2 feet long, branched from the base and hairy. Spines of fruit are sharp enough to puncture bicycle tires and are painful to bare feet. Can also become embedded in fur and fabric.
Identification notes: Mat-forming annual with diffused, branching stems; leaves opposite, with 3 to 9 pairs of elliptic or oblong leaflets; flowers solitary in axils of leaves, flowers of 5 sepals and 5 pale yellow petals; flowers produce spiny nutlets.
Height: 2 inches


Habitat Description: Cultivated areas, along roads, disturbed sites.
Plant Communities: Disturbed Areas
Elevation: Below 7000 feet

Flower Characteristics

Color: Yellow     Shape: Regular not in clusters     Tubular: N     Flowering Period: Mar - Oct
Description: Solitary flowers in axils of smaller or abortive leaves, stems shorter than the subtending leaf; 5 sepals and 5 pale yellow petals .

Leaf and Stem Characteristics

Leaf Color: Dark green     Leaf Type: Compound     Leaf Shape: Round or oval     Leaf Margin: Toothed     Leaf Attachment: Opposite     Leaves Clasp: N
Hairs: Leaves and stems     Spines: N
Leaf Description: Leaf is pinnately compound to 2 inches long with leaflets to 1/2 inch long, lowest pair of leaflets unequal in size.

Fruit and Seed Characteristics

Fruit Color: Brownish-gray   
Fruit Type: Capsule
Fruit Notes: Capsules break into 5 spiny nutlets, each with 2 larger spines; after separation the vicious tacklike nutlets land with larger spines upward. Two-spined segment resembles a goat's head with horns.
Seed Notes: Nutlets or "seeds" are hard and have a pair of 1/4 inch long sharp spines.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 8.0  
Last Updated: Nov 21, 2021
Content Questions/Comments: Email Mary Barnes  
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