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POLYGONACEAE BUCKWHEAT FAMILY

Mihai Costea & James L. Reveal, family description, key to genera; treatment of genera revised in consultation with James L. Reveal, except as noted

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.
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. [Freeman & Reveal 2005 FNANM 5:216–601] 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. —Scientific Editor: Thomas J. Rosatti.

Key to Polygonaceae

EMEX

Mihai Costea

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.
2n=20.
2 species: native to Mediterranean, South Africa, spread worldwide. (Latin: removal from Rumex) Hybrids occur readily when species together; highly sterile when self-pollinated but can backcross with either parent to form viable seeds.

Key to Emex

E. spinosa (L.) Campd. DEVIL'S THORN
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.
Dry, sandy, disturbed places; < 500 m. Central Coast, South Coast; Massachusetts, New Jersey, Florida, Texas; also Hawaii, South America, Eurasia, Africa, Australia; native to Mediterranean. Cleistogamous flowers produced underground. May–Dec {Noxious weed} [Online Interchange]
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.

Previous taxon: Emex australis
Next taxon: Eriogonum

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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Jul 28 2014
Citation for this treatment: [Author of taxon treatment] 2013. Emex, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=24222, accessed on Jul 28 2014

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Bioregions in which Emex spinosa occurs 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.
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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.