Jepson eFlora: Taxon page
Vascular Plants of California
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Tribulus terrestris

Higher Taxonomy
Family: ZygophyllaceaeView DescriptionDichotomous Key
Habit: Annual, perennial herb, shrub, often armed; caudex present or not. Stem: branched; nodes often angled, swollen. Leaf: 1-compound, opposite, petioled; stipules persistent or not; leaflets entire. Inflorescence: flowers 1--2 in axils. Flower: bisexual; sepals 5, free, persistent or not; petals 5, free, generally spreading, twisted (corolla propeller-like) or not; stamens 10, appendaged on inside base or not; ovary superior, chambers (and lobes) 5--10, each with 1--several ovules, placentas axile. Fruit: capsule or splitting into 5--10 nutlets (= mericarps).
Genera In Family: 27 genera, +- 250 species: widespread especially in warm, dry regions; some cultivated (Guaiacum, lignum vitae; Tribulus, caltrop).
eFlora Treatment Author: Duncan M. Porter
Scientific Editor: Thomas J. Rosatti.
Genus: TribulusView Description 

Habit: Annual. Stem: prostrate, spreading radially, generally < 1 m. Leaf: even-1-pinnate; stipules +- leaf-like. Inflorescence: flowers 1 in axils. Flower: sepals deciduous; petals yellow, deciduous. Fruit: 5-lobed, splitting into 5 nutlets, each with many tubercles, 2--4 stout spines; style deciduous; pedicel reflexed. Seed: 3--5 per chamber.
Etymology: (Latin: weapon used to impede cavalry, from armed fruit)
Tribulus terrestris L.
Stem: +- silky or appressed-hairy, also sharply bristly. Leaf: stipules 1--5 mm; leaflets 6--12. Flower: < 5 mm wide; pedicel generally < subtending leaf. Fruit: 5 mm, < 1 cm wide, +- flat, hairy, gray or +- yellow; spines 4--7 mm, spreading, hairy to glabrous.
Ecology: Dry, disturbed areas including roadsides, railways, vacant lots; Elevation: generally < 1000 m. Bioregional Distribution: CA; Distribution Outside California: to Wyoming, eastern United States, central Mexico; native to Mediterranean. Toxicity: TOXIC to livestock in vegetative condition, fruits cause mechanical injury. Flowering Time: Apr--Oct Note: First collected in California in 1902; long a pernicious weed, now controlled by introduced weevils.
Jepson eFlora Author: Duncan M. Porter
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Noxious Weed listed on the CDFA Weed Pest Ratings table
View the CDFA Pest Rating page for Tribulus terrestris
Weed listed by Cal-IPC

Previous taxon: Tribulus
Next taxon: Zygophyllum

Botanical illustration including Tribulus terrestrisbotanical illustration including Tribulus terrestris

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Citation for this treatment: Duncan M. Porter 2012, Tribulus terrestris, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on July 20, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora,, accessed on July 20, 2024.

Tribulus terrestris
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©2012 Keir Morse
Tribulus terrestris
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©2003 Michael Charters
Tribulus terrestris
click for image enlargement
©2012 Keir Morse
Tribulus terrestris
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©2013 California Academy of Sciences
Tribulus terrestris
click for image enlargement
©2012 Keir Morse

More photos of Tribulus terrestris
in CalPhotos

Geographic subdivisions for Tribulus terrestris:
1. You can change the display of the base map layer control box in the upper right-hand corner.
2. County and Jepson Region polygons can be turned off and on using the check boxes.
map of distribution 1

(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurrence).


Data provided by the participants of the  Consortium of California Herbaria.

View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).