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Emex

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

Emex
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.
eFlora Treatment Author: Mihai Costea
Jepson Online Interchange
Key to Emex

Previous taxon: Dodecahema leptoceras
Next taxon: Emex australis

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Citation for this treatment: Mihai Costea 2016. Emex, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=11208, accessed on August 27, 2016.

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