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
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Noxious Weed listed by CDFA
Weed listed by Cal-IPC

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Next taxon: Zygophyllum

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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, /eflora/eflora_display.php?tid=46922, accessed on June 02, 2020.

Citation for the whole project: Jepson Flora Project (eds.) 2020, Jepson eFlora,, accessed on June 02, 2020.

Tribulus terrestris
click for enlargement
© 2009 Neal Kramer
Tribulus terrestris
click for enlargement
© 2012 Keir Morse
Tribulus terrestris
click for enlargement
© 2010 Neal Kramer
Tribulus terrestris
click for enlargement
© 2015 Steve Matson
Tribulus terrestris
click for enlargement
© 2012 Keir Morse
Tribulus terrestris
click for 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 and layers by clicking on the layer control box in the upper right-hand corner.
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3. Filling of Jepson subdivision polygons can be turned off and on in the layer control box.
4. Moving the cursor over any numbered cluster will show the range boundary of the included specimens (with a blue polygon).
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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).


View elevation by latitude chart

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

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).