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.
Species In Genus: +- 12 species: especially dry Africa. 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
Jepson Online Interchange
Noxious Weed

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Botanical illustration including Tribulus terrestris

botanical illustration including Tribulus terrestris


Citation for this treatment: Duncan M. Porter 2012, Tribulus terrestris, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on December 13, 2018.

Citation for the whole project: Jepson Flora Project (eds.) 2018, Jepson eFlora,, accessed on December 13, 2018.

Tribulus terrestris
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© 2003 Michael Charters
Tribulus terrestris
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© 2012 Keir Morse
Tribulus terrestris
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© 2007 Thomas Stoughton
Tribulus terrestris
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© 2015 Steve Matson
Tribulus terrestris
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© 2004 James M. Andre
Tribulus terrestris
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© 2005 James M. Andre

More photos of Tribulus terrestris in CalPhotos

Geographic subdivisions for Tribulus terrestris:
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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 occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

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.