Flora of China 5: 277-350. 2003. POLYGONACEAE 蓼科 liao ke Li Anjen (李安仁 Li An-ren)1, Bao Bojian (包伯坚)1; Alisa E. Grabovskaya-Borodina2, Suk-pyo Hong3, John McNeill4, Sergei L. Mosyakin5, Hideaki Ohba6, Chong-wook Park7 Herbs, shrubs, or small trees, sometimes monoecious or dioecious. Stems erect, prostrate, twining, or scandent, often with swollen nodes, striate, grooved, or prickly. Leaves simple, alternate, rarely opposite or whorled, petiolate or subsessile; stipules often united to a sheath (ocrea). Inflorescence terminal or axillary, spicate, racemose, paniculate, or capitate. Pedicel occasionally articulate. Flowers small, actinomorphic, bisexual, rarely unisexual. Perianth 3–6-merous, in 1 or 2 series, herbaceous, often enlarged in fruit or inner tepals enlarged, with wings, tubercles, or spines. Stamens usually (3–)6–9, rarely more; filaments free or united at base; anthers 2-loculed, opening lengthwise; disk annular (often lobed). Ovary superior, 1-loculed; styles 2 or 3, rarely 4, free or connate at lower part. Fruit a trigonous, biconvex, or biconcave achene; seed with straight or curved embryo and copious endosperm. About 50 genera and 1120 species: worldwide, but primarily N temperate with a few species in tropical regions; 13 genera (two endemic) and 238 species (65 endemic) in China. All Chinese genera belong to the Polygonoideae, a subfamily of some 790 species defined by the presence of ocreae, a monopodial branching pattern, and the lack of an involucre. The Eriogonoideae (330 species) are found only in the New World. Chinese genera of economic importance include Rheum, which has medicinal uses and is also a food plant (rhubarb) in many other regions, and Fagopyrum, which produces a grain (buckwheat). Fallopia nervosa Loureiro is Microcos paniculata Linnaeus (Tiliaceae). Li Anjen, Kao Tsoching, Mao Zumei & Liu Yulan. 1998. Polygonaceae. In: Li Anjen, ed., Fl. Reipubl. Popularis Sin. 25(1): 1–209. 1a. Shrub, rarely a subshrub. 2a. Leaves small, scaly; stamens 12–18; styles 4 ......................................................................................................... 8. Calligonum 2b. Leaves large, not scaly; stamens 6–8; styles 2 or 3. 3a. Tepals 6; stigmas penicillate .................................................................................................................................. 12. Rumex 3b. Tepals 5; stigmas capitate. 4a. Achenes with wings ......................................................................................................................... 10. Parapteropyrum 4b. Achenes without wings. 5a. Stems twining ........................................................................................................................................... 3. Fallopia 5b. Stems erect. 6a. Tepals: inner 3(or 2) enlarged in fruit ............................................................................................ 9. Atraphaxis 6b. Tepals not enlarged in fruit ........................................................................................................... 2. Polygonum 1b. Annual or perennial herb. 7a. Achenes with wings. 8a. Tepals 4; achenes biconvex, margin with wings ................................................................................................... 11. Oxyria 8b. Tepals 5 or 6; achenes trigonous, angles with wings. 9a. Tepals 5; achenes 3-horned at base; stems scandent ............................................................................ 7. Pteroxygonum 9b. Tepals 6; achenes not horned at base; stems erect .......................................................................................... 13. Rheum 7b. Achenes without wings. 10a. Tepals 3 .............................................................................................................................................................. 1. Koenigia 10b. Tepals 5 or 6, rarely 4. 11a. Tepals 6, rarely 4, stigmas penicillate ........................................................................................................ 12. Rumex 11b. Tepals 5, rarely 4; stigmas capitate or fimbriate. 12a. Styles 2, persistent, indurate, elongate in fruit, hooked at apex ................................................... 5. Antenoron 12b. Styles 3, rarely 2, usually deciduous, neither indurate nor elongate in fruit, never hooked at apex. 13a. Stems twining or erect, tepals: outer 3, enlarged in fruit, abaxial surface with wings or keels, rarely not enlarged, without wings or keels. 14a. Stems twining; flowers bisexual; stigmas capitate ....................................................... 3. Fallopia 14b. Stems erect; flowers unisexual, plant dioecious; stigmas fimbriate ......................... 4. Reynoutria 1 Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, People’s Republic of China. 2 V. L. Komarov Botanical Institute, Russian Academy of Sciences, 2 Prof. Popov Street, St. Petersburg, 197376, Russia. 3 Herbarium, Department of Biology, Kyung Hee University, 1 Hwaegi-dong, Dongdaemoon-ku, Seoul 130-701, South Korea. 4 Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, Scotland, United Kingdom. 5 Vascular Plants Department, M. G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska Street, Kiev 01601, Ukraine. 6 University Museum, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. 7 Herbarium, School of Biological Sciences, Seoul National University, Seoul 151-742, South Korea. POLYGONACEAE 13b. Stems erect; tepals not enlarged in fruit, rarely enlarged, becoming fleshy. 15a. Achenes trigonous, much longer than or rarely equaling persistent perianth ......... 6. Fagopyrum 15b. Achenes trigonous or biconvex, shorter than or rarely longer than persistent perianth ...................................................................................................................... 2. Polygonum 1. KOENIGIA Linnaeus, Syst. Nat., ed. 12, 2: 71, 104. 1767; Mant. Pl. 1: 3, 35. 1767. 冰岛蓼属 bing dao liao shu Li Anjen (李安仁 Li An-ren); Alisa E. Grabovskaya-Borodina Herbs annual. Stems slender, branched. Leaves petiolate, subopposite; ocrea membranous. Inflorescence paniculate. Flowers bisexual. Perianth 3(–5)-parted. Stamens 3, alternate with tepals and 3 glandlike staminoids. Ovary ovoid, compressed; styles 2, persistent, very short; stigmas capitate. Achenes narrowly ovoid, biconvex. About three species: Arctic regions, Asia, N Europe, North America; one species in China. 1. Koenigia islandica Linnaeus, Syst. Nat., ed. 12, 2: 104. cuneate, margin entire, apex obtuse; ocrea lax, brown, 1.5–2 1767; Mant. Pl. 1: 35. 1767. mm, thinly membranous. Flowers axillary, fascicled. Perianth greenish, 3-parted; tepals broadly elliptic, ca. 1 mm. Stamens 3, 冰岛蓼 bing dao liao shorter than perianth. Styles 2 or 3, very short; stigmas 2(or 3), capitate. Achenes brown, dull, 1.2–1.5 mm, granular. Fl. Jul– Polygonum islandicum (Linnaeus) J. D. Hooker. Aug, fr. Aug–Sep. 2n = 28. Herbs annual, dwarf. Stems erect, usually tufted, reddish, Alpine meadows, wet grasslands, valleys; 2000–4900 m. Gansu, 3–8 cm tall, slender, glabrous; branches spreading. Leaves Qinghai, Shanxi (Wutai Shan), Sichuan, Xinjiang, Xizang, Yunnan alternate, rarely opposite above; petiole 1–3 mm, glabrous; leaf [Bhutan, NW India, Kashmir, Kazakhstan, Kyrgyzstan, Mongolia, Ne- blade broadly elliptic, obovate, or nearly orbicular, 3–5 × 2–4 pal, Pakistan, Russia, Sikkim; Arctic regions, N Europe, North Amer- mm, both surfaces glabrous, sparsely puncticulate, base broadly ica]. 2. POLYGONUM Linnaeus, Sp. Pl. 1: 359. 1753, nom. cons. 蓼属 liao shu Li Anjen (李安仁 Li An-ren); Alisa E. Grabovskaya-Borodina, Suk-pyo Hong, John McNeill, Hideaki Ohba, Chong-wook Park Herbs, rarely subshrubs, or small shrubs, rarely dioecious. Stems erect, prostrate, or ascending, usually with conspicuously swollen nodes, glabrous or pubescent, rarely prickly. Leaves simple, alternate, subsessile; leaf blade variously shaped, margin entire; ocrea tubular, membranous, margin entire or lacerate, apex truncate or oblique. Inflorescence terminal or axillary, racemose, spicate, capitate, or paniculate, sometimes flowers fascicled or solitary in axils of leaves. Pedicel often articulate. Flowers bisexual, rarely unisexual; bracts and bracteoles membranous. Perianth persistent, 5(or 4)-parted. Stamens 7 or 8, rarely 4. Styles 2 or 3, deciduous, mostly elongate. Achenes trigonous or biconvex, rarely biconcave. About 230 species: worldwide, mostly in N temperate regions; 113 species (23 endemic) in China. Treatments of Polygonum and related genera (subfamily Polygonoideae), e.g., those by Haraldson (Symb. Bot. Upsal. 22(2): 1–95. 1978) and Ronse Decraene & Akeroyd (Bot. J. Linn. Soc. 98: 321–371. 1988), have segregated species of Polygonum in the broad sense adopted here into two separate tribes, Polygoneae and Persicarieae. As represented in China, the former is restricted to P. sect. Polygonum, i.e., species 1–16 below (Polygonum s.str.), along with various other genera, e.g., Fagopyrum (incl. Pteroxygonum) by Haraldson, and Fallopia (incl. Reynoutria) by Ronse Decraene & Akeroyd. The remainder of Polygonum in the broad sense (species 17–113 below) is generally assigned to Persicaria (or a varying number of segregate genera, such as Aconogonon and Bistorta) which, with Antenoron and Koenigia (and Fagopyrum, incl. Pteroxygonum by Ronse Decraene & Akeroyd), comprises the tribe Persicarieae. Of the six sections of Polygonum recognized here, the first,