Polygonaceae Juss.

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Herbs, shrubs, lianas (stem or tendril climbers) or trees; without latex or exudate

Morphology Leaves Stipules

Stipules usually present, connate to form a leaf sheath (ochrea), rarely absent (subfam. Eriogoneoideae), leaf sheath tubular, membranaceous or scarious, deciduous or persistent, with bilobed or fringed margins

Morphology Leaves

Leaves simple, alternate (rarely opposite), usually spirally arranged; petiolate or subsessile, petioles often flattened; extrafloral nectaries sometimes present at petiole base; leaf-blades entire, pinnately veined; basally auriculate, cordate, hastate, sagittate, rounded to cuneate, margins entire, sometimes crenate

Morphology Reproductive morphology Flowers

Flowers usually hermaphrodite, small, if unisexual then plants monoecious, polygamo- monoecious or dioecious; inflorescence cymose, terminal, or in axillary racemes, corymbs, spikes and heads, sometimes in axillary fascicles; involucral bracts sometimes present, developed and showy, regular, 2-5- merous, cyclic to partially acyclic; hypanthium, when present, free, hypogynous disk or nectaries present between the androecial members; calyx and corolla distinct, or both sepal -like or petal -like, 2-6, free or joined, 1-2- whorled or spiralled, persistent in fruit and often accrescent; stamens (2-)6(-9) to many (Symmeria Benth.), free or adnate to the perianth (usually more or less perigynous), free or connate; gynoecium (2-)3 carpelled, syncarpous, styles 2-3, free to partially jointed, apical, stigmas 2-3, ovary superior, unilocular, uniovulate, placentation basal, orthotropous

Morphology Reproductive morphology Fruits

Fruit dry, indehiscent usually a trigonous or flattened nut or achene -like, sometimes enclosed by a fleshy hypanthium or perianth, 1 seeded

Morphology Reproductive morphology Seeds

Seeds with ruminate (Coccoloba P. Browne) or not- ruminate endosperm, oily, starchy, cotyledons 2, embryo straight to curved.

Note

Number of genera: Antigonon (6 species). Coccoloba (120 species). Gymnopodium (3 species). Leptogonum (one species endemic to Hispaniola). Muehlenbeckia (9 species). Neomillspaughia (2 species). Persicaria (c. 5 species). Podopterus (3 species). Polygonum (c. 30 species). Rumex (c. 15 species). Ruprechtia (37 species). Symmeria (1 species). Triplaris (18 species). Notes on delimitation: Traditionally the Polygonaceae were placed within the Caryophyllales on the basis of the unilocular ovary and single, basalovule. However, recent studies have revealed that the family lacks the P-type sieve-tube plastids, anatropous ovules, betalain pigments and perisperm characters that characterise the order Caryophyllales. Recent studies by the APG II (2003) still include the Polygonaceae within the Caryophyllales.

Diagnostic

See below. Coccoloba - erect or climbing woody plants, unisexual flowers and pedunculate fleshy fruits. Ruprechtia - trees to shrubs, three-winged fruits, female partial inflorescences 2-3-flowered, male flowers pedicellate, twigs often solid. Triplaris - shrubs to trees, three-winged fruits, female partial inflorescences 1-flowered, male flowers sessile, often associated with ants that live in its hollow branches. Polygonum - erect herbs with flowers in spikes, closely allied to Persicaria. Antigonon - climbing plants with showy bracts protecting inflorescences. Distinguishing characters (always present): Stems often with conspicuous swollen nodes. Stipules present. Ochreas are present in the Polygonoideae, absent in the Eriogonoideae (this subfamily is not represented in the Neotropics). Flowers small, often unisexual (Coccoloba), sometimes with attractive bracts (Antigonon). Fruits with accrescentcalyx (Triplaris). Key differences from similar families: Polygonaceae are characterised by the presence of the ochrea (absent from subfam. Eriogonoideae), and have leaves spirally alternate, swollen nodes and involucred inflorescence. Vegetatively they can be confused with Piperaceae (swollen nodes, leaves with irregular base) but they have a deciduousterminalstipule and very small flowers densely arranged in spikes.

Distribution

While Coccoloba, Ruprechtia and Triplaris are endemic to the Neotropics, Rumex, Polygonum and Antigonon have weedy status, with species of knot-weed (Polygonum) being particularly invasive in Europe. Antigononleptopus Hook. & Arn. originates from Mexico but is cultivated worldwide because of its showy flowers. Buckwheat, used in Japan for making pasta (soba, Fagopyrumesculentum Moench) is an increasingly popular, gluten-free alternative to wheat. The Polygonaceae are cosmopolitan, with most genera and species occurring in northern temperate regions. 31 genera are found in the western hemisphere. 16 of these genera are restricted to western North America, with 3 disjunct to Chile and Argentina. Of the 13 tropical and subtropical American genera: Ruprechtia C.A.Mey., Triplaris Loefl., and Coccoloba P.Browne are fairly widespread in the Neotropics; Neomillspaughia S.F.Blake, Podopterus Kunth, Gymnopodium Rolfe and Antigonon Endl. are restricted to Central America. The monotypicLeptogonum Benth. is endemic to Hispaniola. Symmeria Benth. is amphiatlantic. Muehlenbeckia Meisn. is amphipacific. Polygonum L., Rumex L., and Persicaria L. are cosmopolitan.

Polygonaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Morphology General Habit

Herbs, shrubs or climbers, rarely trees: leaves alternate, with the base of the petiole often dilated into a membranous sheath (ochrea)

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, polygamous or dioecious, actinomorphic, small and inconspicuous

Morphology Reproductive morphology Flowers Calyx

Sepals 3–6, imbricate, often enlarged and becoming membranous in fruit

Morphology Reproductive morphology Flowers Corolla

Petals absent

Morphology Reproductive morphology Flowers Androecium

Stamens usually 6–9, rarely more; filaments free or united at the base; anthers 2-celled, opening lengthwise

Morphology Reproductive morphology Flowers Nectaries

Disk annular or central

Morphology Reproductive morphology Flowers Gynoecium

Ovary superior, sessile, 1-celled; styles 2–4, usually free; ovule solitary, basal, sessile or stalked

Morphology Reproductive morphology Fruits

Fruit an indehiscent trigonous or 2-sided nut

Morphology Reproductive morphology Seeds

Seeds with abundant mealy endosperm and often excentric embryo

Distribution

Besides the above indigenous genera, Antigonon leptopus Hook. & Arn., a native of Mexico, is often met with; it is widely cultivated as an ornamental and is known as "Corallita."

Gemma Bramley, Anna Trias-Blasi & Richard Wilford (2023). The Kew Temperate Plant Families Identification Handbook. Kew Publishing Royal Botanic Gardens, Kew

Recognition

Characters of similar families: Caryophyllaceae: ocrea absent, leaves opposite, petals usually present (0–1)4–5. Plumbaginaceae: nodes swollen but ocrea absent, stipules absent.

Morphology General Habit

Trees, shrubs, vines or herbs, latex absent

Morphology Stem

Stems prostrate to erect, nodes often swollen, rarely tendrils

Morphology Leaves Stipules

Stipules present, rarely absent, often with a nodal sheath (ocrea) (Polygonoideae), cylindric to funnelform, chartaceous, membranous or foliaceous

Morphology Leaves

Leaves simple, basal, or basal and cauline, forming rosette, mostly alternate (some sub-opposite), margins mostly entire, occasionally lobed

Morphology Reproductive morphology Inflorescences

Inflorescences terminal or axillary, spicate, racemose, paniculate or solitary, bracts absent or 2–10, foliaceous or scale-like, peduncle present or absent, flowers subtended by involucral bracts or enclosed in tubular involucres or subtended by connate bracteoles forming a persistent membranous tube (ocreola)

Morphology Reproductive morphology Flowers

Flowers small, actinomorphic, usually bisexual, 1– many; perianth persistent, often accrescent in fruit, green, white, yellow, red, or purple, campanulate to urceolate, sometimes membranous, or fleshy, glabrous or pubescent sometimes glandular; tepals (3)5–6 free or forming a tube, usually in 2 whorls; stamens (1)6–9(–18), staminodes rarely present, filaments free or forming a tube; ovary superior, carpels 2–4 united to form 1 locule, styles 1–3(4), stigmas 1 per style

Morphology Reproductive morphology Fruits

Fruits achenes, trigonous or lenticular nut, winged or unwinged, glabrous or pubescent, yellow, brown, red, or black

Morphology Reproductive morphology Seeds

Seeds 1.

Distribution

Polygonaceae has 55 genera, ca.1,000 species in two subfamilies, Polygonoideae and Eriogonoideae. The family is cosmopolitan and common in northern temperate regions. The largest genera are Polygonum (ca. 250 species), Rumex (ca. 200 species), Eriogonum (ca. 200 species), Persicaria (ca. 100 species) and Calligonum (ca. 80 species).

Note

Mostly herbs, stems with swollen nodes and characteristic ocrea (not Eriogonoideae). Leaves alternate. Flowers small and subtended by involucral bracts. Fruits achene-like, or a dry trigonous or flattened nut.

Description Author

Nicky Biggs

Polygonaceae, R. A. Graham. Flora of Tropical East Africa. 1958

Morphology General Habit

Herbs, climbers, shrubs, or trees (not in tropical East Africa)

Morphology Stem

Branches sometimes tendrilous

Morphology Leaves

Leaves usually alternate, often lush, sessile or stalked, usually dilated into an amplexicaul cup (ocrea) at the junction with the stem

Morphology Reproductive morphology Flowers

Flowers actinomorphic; hermaphrodite, polygamous, dioecious, or monoecious; borne in many- or few-flowered fascicles, pedicellate, subtended or not by ocreiform bracts with or without bracteoles

Morphology Reproductive morphology Inflorescences

Inflorescence capitate, racemose, or ± umbellate, often branched and paniculate

Morphology Reproductive morphology Flowers Corolla

Petals 0

Morphology Reproductive morphology Flowers Perianth

Perianth inferior, calyciform with 3–6 free, sometimes petaloid lobes (tepals) arranged in 1 or 2 series, often accrescent and then sometimes armed with spines, prickles or teeth

Morphology Reproductive morphology Flowers Androecium

Stamens 5–9 inE. African spp., usually all fertile, inserted in 1 or 2 series at or near the base of the perianth; filaments filiform throughout or basally dilated, free or conjoined at the base; anthers 2–celled, longitudinally dehiscent

Morphology Reproductive morphology Flowers Gynoecium

Ovary 1–locular, superior, sessile Ovule solitary, basal, sessile or stalked Styles 2–3, free or connate below, the flowers sometimes heterostylous; stigmas capitate, dilated, fimbriate or penicillate

Morphology Reproductive morphology Fruits

Mature fruit nut-like, fusiform, lenticular, or acutely or obscurely trigonous, unarmed or armed with prickles or (Harpagocarpus) barbed setae

Morphology Reproductive morphology Seeds

Seed with abundant endosperm

Distribution

Two genera are confined to Africa and Madagascar A world-wide family, most abundant in temperate regions

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit

Herbs, shrubs or trees of various habit; leaves alternate, simple, mostly entire, the petiole often dilated and clasping; stipules of characteristic tubular form (ocreae) ensheathing the stem above each leaf-base (except in Antigonon)

Morphology Reproductive morphology Flowers

Flowers small, regular, perfect or unisexual, in terminal and axillary racemose inflorescences; perianth of 3–6 segments, persistent after flowering, sometimes becoming fleshy

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3–9 from a central disc, the filaments free or fused at the base; anthers 2-celled, dehiscent by longitudinal slits

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary superior, 1-celled, with usually 3 styles; ovule 1, basal, sessile or erect at the apex of an elongate funicle.

Morphology Reproductive morphology Fruits

Fruit an achene, trigonous or compressed, usually surrounded by the persistent perianth; seed often grooved or lobate, with abundant endosperm, the embryo usually lateral and either curved or straight.

Distribution

A family of about 30 genera and 800 species, of wide geographic distribution but the majority in temperate regions.

Flora Zambesiaca. Vol. 9, Part 3. Polygonaceae-Myriaceae. Pope GV, Polhill RM, Martins ES. 2006.

Morphology Branches

Branches sometimes with tendrils

Morphology Reproductive morphology Inflorescences

Inflorescences capitate, racemose or ± umbellate, sometimes branched and paniculate, the flowers usually fascicled and subtended by bracts as well as the ocrea, with or without bracteoles Inflorescences capitate, racemose or ± umbellate, sometimes branched and paniculate, the flowers usually fascicled and subtended by bracts as well as the ocrea, with or without bracteoles

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, polygamous or unisexual, sometimes heterostylous, actinomorphic, pedicellate; pedicels usually articulated Flowers hermaphrodite, polygamous or unisexual, sometimes heterostylous, actinomorphic, pedicellate; pedicels usually articulated

Morphology Reproductive morphology Flowers Perianth

Perianth sepaloid or petaloid of 3–6 free or connate segments (tepals), in 1 or 2 series, imbricate in bud, membranous, sometimes accrescent, sometimes armed with spines, prickles or teeth Perianth sepaloid or petaloid of 3–6 free or connate segments (tepals), in 1 or 2 series, imbricate in bud, membranous, sometimes accrescent, sometimes armed with spines, prickles or teeth

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens (4)6–9, usually inserted at or near the base of the perianth segments; filaments filiform or dilated at the base, free or basally united; anthers dorsifixed, 2-thecous, opening lengthwise

Morphology Reproductive morphology Flowers Disc

Disk annular or composed of glands

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary superior, syncarpous, unilocular, sometimes falsely 3-locular, with a solitary basal orthotropous ovule; styles 2–3, free, or connate at the base; stigmas capitate, peltate or penicillate

Morphology Reproductive morphology Fruits

Fruit a nut, indehiscent, hard, trigonous or lenticular, usually enclosed in the ± persistent perianth Fruit a nut, indehiscent, hard, trigonous or lenticular, usually enclosed in the ± persistent perianth

Morphology Reproductive morphology Seeds

Seed similar in shape to the nut, with abundant endosperm; testa membranous, smooth or not. Seed similar in shape to the nut, with abundant endosperm; testa membranous, smooth or not

Note

Rheum × hybridum Murray, rhubarb, with cordate leaves up to 1 m long, is sometimes grown for its edible petioles. Bistorta amplexicaulis (D. Don) Greene (Polygonum amplexicaule D. Don), from the Himalayan region, has been grown as a garden ornamental in Zimbabwe, e.g. Harare, Cleveland Dam, private garden, fl. 15.iii.1969, Biegel 2905 (K; SRGH). It is a rhizomatous perennial with stems to 1 m from a rosette of basal leaves; stem leaves ovate, upper ones amplexicaul; flowers blood-red, c. 4 mm long, in spiciform panicles. Bistorta is similar to Persicaria, differing in its rhizomatous rootstock and basal leaves.

Distribution

A family with c. 43 genera and about 1100 species, cosmopolitan and mainly north temperate, but also in tropical regions.

Morphology General Habit

Annual or perennial herbs, shrubs or climbers (more rarely trees), glabrous or hairy Annual or perennial herbs, shrubs or climbers (more rarely trees), glabrous or hairy

Morphology Stem

Branches sometimes with tendrils

Morphology Leaves

Leaves usually alternate and usually with sheathing stipules (ocreae) Leaves usually alternate and usually with sheathing stipules (ocreae)

Morphology Reproductive morphology Flowers Androecium

Stamens (4)6–9, usually inserted at or near the base of the perianth segments; filaments filiform or dilated at the base, free or basally united; anthers dorsifixed, 2-thecous, opening lengthwise

Morphology Reproductive morphology Flowers Nectaries

Disk annular or composed of glands

Morphology Reproductive morphology Flowers Gynoecium

Ovary superior, syncarpous, unilocular, sometimes falsely 3-locular, with a solitary basal orthotropous ovule; styles 2–3, free, or connate at the base; stigmas capitate, peltate or penicillate

Ghazanfar, S. A., Edmondson, J. R. (Eds). (2016). Flora of Iraq, Volume 5, Part 1: Elatinaceae to Sphenocleaceae. Kew Publishing

Morphology General Habit

Shrubs, climbers and perennial, sometimes annual or biennial, herbs

Morphology Leaves

Leaves usually alternate, simple, petiolate to sessile; stipules fused into a sheath (ochrea) clasping the stem

Morphology Reproductive morphology Inflorescences

Inflorescences spicate, fasciculate or paniculate, flowers hermaphrodite or unisexual, actinomorphic. Perianth 3-6-merous, segments fused below, often accrescent in fruit

Morphology Reproductive morphology Flowers Corolla

Petals absent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 6–9(–16), anthers medifixed

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary superior, 1-locular; styles 2–4; ovule 1, basal-Fruit a nut, usually trigonous or lenticular, often enclosed by the persistent perianth.

Distribution

A large family of 46 genera and 1200 species, ± cosmopolitan, but predominantly in the northern temperate regions.

Use

Certain species have value as crops, as vegetables, or as medicines

Use

Few of them are economically important, but buckwheat (Fagopyrum sagittatum Gilib.) is a widely grown Asiatic species whose seeds produce a kind of flour.