Jepson eFlora: Taxon page
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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.
eFlora Treatment Author: Duncan M. Porter
Jepson Online Interchange
Noxious Weed

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botanical illustration including Tribulus terrestris


Citation for this treatment: Duncan M. Porter 2016. Tribulus terrestris, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on April 30, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on April 30, 2016.

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

More photos of Tribulus terrestris in CalPhotos

Geographic subdivisions for Tribulus terrestris:
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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.
Blue line denotes eFlora flowering time.