Description from Flora of China
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.
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, P. sect. Polygonum, represents Polygonum in the narrow sense, and the remaining five either fall within a broadly defined genus, Persicaria, or are variously recognized as distinct genera, e.g., Aconogonon and Bistorta by Haraldson. As circumscribed in earlier work (e.g., Meisner in Candolle, Prodr. 14(1), 1856), P. sect. Cephalophilon included a number of species now treated as belonging to the genus Koenigia; Ronse Decraene & Akeroyd (op. cit.) treated the residue of P. sect. Cephalophilon and P. sect. Echinocaulon as components of an expanded Persicaria sect. Persicaria.
The following taxa have been described or reported from China, but we have seen no specimens and are therefore unable to treat them in this account. Further revisionary study is necessary.
Polygonum minutissimum Z. Wei & Y. B. Chang (Bull. Bot. Res., Harbin 12: 271. 1992, not L. O. Williams, 1934), described from Zhejiang.
Polygonum pilushanense Y. C. Liu & C. H. Ou (Quart. J. Chinese Forest. 8: 123. 1976), described from Taiwan.
One of us (Ohba) adds the following species described under Bistorta; however, one of us (Li) has been unable to examine material because of health reasons. We list them here pending further revisionary work on the family.
Bistorta albiflora Miyamoto & H. Ohba (Bull. Nat. Sci. Mus. Tokyo, ser. B, 28: 141. 2002), described from Sichuan.
Bistorta longispicata Yonekura & H. Ohashi (J. Jap. Bot. 76: 346. 2001), described from Xizang.
Bistorta ludlowii Yonekura & H. Ohashi (J. Jap. Bot. 76: 348. 2001), described from SE Xizang.
Bistorta sherei H. Ohba & S. Akiyama (Alp. Fl. Jaljale Himal. 11. 1992), reported from Xizang (see Bull. Nat. Sci. Mus. Tokyo, ser. B, 28: 145. 2002).
Bistorta tubistipulis Miyamoto & H. Ohba (Bull. Nat. Sci. Mus. Tokyo, ser. B, 28: 143. 2002), described from Sichuan.
About 230 species: worldwide, mostly in N temperate regions; 113 species (23 endemic) in China.
(Authors: Li Anjen (李安仁 Li An-ren); Alisa E. Grabovskaya-Borodina, Suk-pyo Hong, John McNeill, Hideaki Ohba, Chong-wook Park)