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Emex spinosa
DEVIL'S THORN

Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key

Common Name: BUCKWHEAT FAMILY
Habit: Annual to shrub [tree]. Stem: nodes swollen or not. Leaf: simple, basal or cauline, generally alternate; ocreae present or 0, generally scarious, persistent or not. Inflorescence: flower clusters in axillary to terminal cyme-, panicle-, raceme-, spike-, umbel- or head-like arrangements, entire inflorescence or main inflorescence branches generally subtended by bracts ("inflorescence bracts"); peduncles present or 0; flower clusters in Eriogoneae-Eriogonoideae subtended by involucre of >= 1 free or +- fused, sometimes awn-tipped bracts ("involucre bracts") or, in Polygonoideae and rarely in Eriogonoideae, not (if bracts completely fused, involucre "tubular"); pedicels in Eriogoneae each often subtended by 2 free, transparent, linear bractlets or in Polygonoideae all subtended by 2+ fused, membranous, wide bractlets. Flower: generally bisexual, small, 1--200 per node; perianth parts 2--6, generally in 2 whorls, free or basally fused, generally petal-like, often +- concave adaxially, often darker at midvein, often turning +- red or +- brown in age; stamens [1]3 or 6--9 in 2 whorls; ovary superior, 1-chambered, ovule 1, styles 1--3. Fruit: achenes, included in or exserted from perianth, generally 3-angled, ovoid or elliptic, generally glabrous.
Genera In Family: 48 genera, +- 1200 species: worldwide, especially northern temperate; some cultivated for food (Coccoloba, sea-grape; Fagopyrum, Rheum, Rumex) or ornamental (Antigonon, lovechain; Coccoloba; Muehlenbeckia; Persicaria; Polygonum), a few timbered (Coccoloba; Triplaris). Several (Emex; Fallopia; Persicaria; Polygonum; Rumex) are weeds. Note: Treatment of genera in Eriogonoideae based on monographic work of James L. Reveal. Involucre number throughout is number (1--many) per ultimate grouping, at tips of ultimate branches; flower number is per flower cluster or involucre, unless otherwise stated. Fagopyrum esculentum Moench not naturalized, considered an historical waif (or garden weed +- presently), therefore not treated.
eFlora Treatment Author: Mihai Costea, except as noted
Genus: EmexView DescriptionDichotomous Key

Habit: Annual, glabrous; monoecious. Stem: decumbent to erect, 1--8 dm, base often +- red. Leaf: cauline, alternate, petioled; ocrea soon torn, falling; blade +- hastate to cordate. Staminate Inflorescence: axillary, terminal, raceme-like; flowers 1--8. Pistillate Inflorescence: axillary, spike-like; flowers 1--8. Staminate Flower: perianth parts 5--6, free; stamens 4--6. Pistillate Flower: perianth parts 6, fused; outer 3 spine-tipped in fruit, inner 3 tubercled; styles 3, free. Fruit: included, 2--4.5 mm, ovate, shiny, spines 3; perianth hardened. Chromosomes: 2n=20.
Species In Genus: 2 species: native to Mediterranean, South Africa, spread worldwide. Etymology: (Latin: removal from Rumex) Note: Hybrids occur readily when species together; highly sterile when self-pollinated but can backcross with either parent to form viable seeds.

Emex spinosa (L.) Campd.
NATURALIZED
Stem: 3--6(8) dm. Leaf: petiole 1.5--4 cm, blade 3--13 cm, 1--12 cm wide. Fruit: perianth 3-angled, each face with 8--12 pit-like depressions, spines 1.5--3 mm.
Ecology: Dry, sandy, disturbed places; Elevation: < 500 m. Bioregional Distribution: CCo, SCo; Distribution Outside California: Massachusetts, New Jersey, Florida, Texas; also Hawaii, South America, Eurasia, Africa, Australia; native to Mediterranean. Flowering Time: May--Dec Note: Cleistogamous flowers produced underground.
Unabridged Note: According to Art Gibson, plants behind the dunes at Zuma Beach have basal leaves as well as dimorphic fruits, with those in the axils of basal leaves often spineless as well as larger than the others.
eFlora Treatment Author: Mihai Costea
Jepson Online Interchange
Noxious Weed

Previous taxon: Emex australis
Next taxon: Eriogonum

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botanical illustration including Emex spinosa

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Citation for this treatment: Mihai Costea 2016. Emex spinosa, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=24222, accessed on September 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on September 27, 2016.


Geographic subdivisions for Emex spinosa:
CCo, SCo;
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.
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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).

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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.