POLYGONACEAE 



411 



more widely spreading; achenes compressed-trigonous, dull. 



Aug.-Oct. Wet sunny places in lowlands; Honshu, Shi- 



koku, Kyushu; rather common. Korea. 



31. Polygonum hydropiper L. Persicaria hydropiper 



(L.) Spach; Persicaria vernalis Nakai Yanagi-tade, Ma- 



TADE. Annual; stems often profusely branched, erect, 40- 

 80 cm. long, glabrous; leaves lanceolate to narrowly ovate, 3-12 

 cm. long, 1-3 cm. wide, acuminate to obtuse, acute at base, 

 short-petiolate, essentially glabrous, slightly scabrous on 

 margin, the underside with obscure impressed discoid glands; 

 sheaths short-tubular, membranous, glabrous, ciliate; spikes 

 slender, narrow, nodding, 5-10 cm. long, sometimes shorter 

 and included within the sheath, loosely flowered, the bracts 

 usually sparingly short-ciliate; perianth green-yellow, reddish 

 on the upper portion, 2.5-4 mm. long; achenes flattened, 

 black, punctulate, dull, ovate to ovate-orbicular, 2-3 mm. long. 



Aug.-Oct. Wet places in lowlands and hills, especially 



along rivers and streams; Hokkaido, Honshu, Shikoku, Kyu- 

 shu; very common and exceedingly variable. Widely dis- 

 tributed in the N. Hemisphere. Cv. Fastigiatum. P. hydro- 

 piper var. fastigiatum Makino; P. jastigiatoramosum Ma- 

 kino; P. maximotviczii Regel; P. hydropiper vat. maximoiviczii 

 (Regel) Makino Azabu-tade. Slender cultivar with nar- 

 row, smaller leaves and flowers; achenes about 1.5 mm. long; 



used as flavoring. Forma angustissimum Makino. Ito- 



TADE. Very slender phase with nearly linear leaves. 



Forma gramineum (Meissn.) Ohwi. P. gramineiim Meissn. 



Satsuma-tade. Allied to f. angustissimum; the petioles 



1-2.5 cm. long, distinct. 



32. Polygonum pubescens Bl. P. flaccidum sensu auct., 

 non Roxb.; Persicaria rottleri Hara, excl. syn.; Persicaria fiac- 



cida Nakai, excl. syn. Bontoku-tade. Annual; stems 



erect, branched, 40-80 cm. long, glabrous or appressed short- 

 pubescent; leaves lanceolate to broadly so, 5-10 cm. long, 

 1-2.5 cm. wide, acuminate, gradually narrowed below to the 

 short petiole, appressed short-pubescent, at least on the nerves 

 beneath, often dark blotched on the middle above, and with 

 scattered, obscure, impressed glands, the sheaths tubular, mem- 

 branous, 8-13 mm. long, short-pilose, with cilia 3-8 mm. long; 

 spikes narrowly linear, nodding, loosely flowered, 5-10 cm. 

 long, the bracts strigose-ciliate; flowers about 3 mm. long, the 

 perianth-segments green on the lower half, reddish on upper 

 half, glandular-dotted; achenes about 2 mm. long, trigonous, 



ovoid, black, punctulate, lustreless. Sept.-Oct. Wet places; 



Honshu, Shikoku, Kyushu; common.^ — ^Korea, China, For- 

 mosa, Ryukyus, Malaysia, and India. 



33. Polygonum viscoferum Makino. Persicaria visco- 



fera (Makino) Gross Nebari-tade. Annual with long 



ascending coarse hairs; stems simple or branched at base, erect, 

 radier thick, 40-80 cm. long; leaves lanceolate or broadly so, 

 4-10 cm. long, 1-2 cm. wide, acuminate, obtuse to subacute at 

 die subsessile base; sheaths tubular, 5-10 mm. long, ciliate; 

 spikes several to more than 10, erect, 3-5 cm. long, rather 

 densely many-flowered, the peduncles on the upper part and 

 the upper internodes viscid; flowers greenish or rarely with a 

 reddish tinge, pedicellate, about 2 mm. long; achenes black, 



lustrous, trigonous, obovoid, 1.8-2 mm. long. July-Sept. 



Waste ground in hills and foothills; Hokkaido, Honshu, Shi- 

 koku, Kyushu. Ryukyus and Korea. 



Var. robustum Makino. P. ma^inoi Nakai; Persicaria 



mal^inoi (Nakai) Nakai; Polygonum excurrens Steward 



0-nebari-tade. Relatively large, erect, less hairy, loosely 



pilose and appressed short-strigose on leaves above or toward 



margin; flowers greenish. Waste ground in hills and low 



mountains; Hokkaido, Honshu, Kyushu. Korea. 



34. Polygonum persicaria L. Persicaria vulgaris Webb 



& Moq.; Persicaria mitis auct. Japon., non Gilib. Haru- 



TADE. Erect annual 20-50 cm. high; stems rather soft, the 

 branches ascending at base, glabrous or often pubescent; leaves 

 lanceolate or broadly so, 6-12 cm. long, 1-3 cm. wide, obtuse, 

 acute at base, loosely short-pilose or glabrous except on the 

 nerves and margin, short-petioled, the lateral nerves not promi- 

 nent, 7 to 10 pairs, the sheaths thin-membranous, 3-10 mm. 

 long, glabrescent, widi cilia 1-2 mm. long; spikes few, termi- 

 nal, cylindric, erect, 2-5 cm. long, densely many-flowered, the 

 peduncles sometimes loosely glandular-pilose; flowers reddish, 

 2.5-3 mm. long, die perianth-segments with very slender 

 nerves; achenes ovate-orbicular, compressed or trigonous, black- 

 brown, lustrous, about 2 mm. long. May-June (Oct.). 



Hokkaido, Honshu, Shikoku, Kyushu; rather common. 



Eurasia and N. America. 



35. Polygonum caespitosum Bl. var. laxiflorum Meissn. 

 P. yo\usaianum Makino; Persicaria yo\usaiana (Makino) Na- 

 kai; Polygonum caespitosum subsp. yoktisaianum (Makino) 

 Danser Hana-tade. Slender, decumbent, branched, gla- 

 brescent annual; leaves thinly membranous, ovate to narrowly 

 so, sometimes broadly lanceolate, 3-7 cm. long, 1.5-3 cm. wide, 

 abrupdy acuminate, caudate at tip, vivid green, loosely 

 ascending-pilose above and on nerves beneath, short-petio- 

 late; sheaths 3-8 mm. long, tubular, the cilia about as long 

 as the sheath; spikes several, linear, 3-10 cm. long, loosely 

 flowered, often interrupted; flowers clear pinkish, 2-3 mm. 

 long; achenes dark brown, lustrous, trigonous, ovoid, about 



2 mm. long. Aug.-Sept. Woods in foothills; Hokkaido, 



Honshu, Sliikoku, Kyushu; rather common. Korea and 



China. The typical phase occurs in Formosa and Malaysia. 



36. Polygonum longisetum de Bruyn. P. blumei 

 Meissn.; P. \inashii Lev. & Van't.; Persicaria longiseta (de 



Bruyn) Kitag.; Persicaria blumei (Meissn.) Gross Inu- 



tade. Annual, usually more or less pubescent; stems erect 

 or ascending, branched, decumbent at base, glabrous; leaves 

 broadly lanceolate to narrowly oblong-ovate, deep green, 4-8 

 cm. long, 1-2.5 cm. wide, gradually narrowed and obtuse at 

 tip, acute at base, glabrous or appressed short-pilose above and 

 on nerves beneath, short-petiolate; sheaths 5-10 mm. long, the 

 cilia about as long as the sheath; spikes several, terminal, cyl- 

 indric, rather densely many-flowered, erect; flowers reddish, 

 2-2.5 mm. long; achenes black-brown, lustrous, trigonous, 



ovoid, 1.8-2.2 mm. long. Juiy-Nov. Wet, grassy, sunny 



places in lowlands; Hokkaido, Honshu, Shikoku, Kyushu; 



very common. Korea, China, Ryukyus, and Malaysia. 



Forma albiflonim (Makino) Ohwi. P. blumei var. albi- 



fiorum Makino Shirobana-inu-tade. A rare phase with 



white flowers. 



37. Polygonum kawagoeanum Makino. Persicaria 

 katcagocana (Makino) Nakai; Polygonum minus subsp. pro- 



ccrum Danser Shima-hime-tade. Annual, 30-60 cm. 



high; stems somewhat tufted, erect from branched decumbent 

 base, usually red-brown, slender, with slighdy thickened 

 nodes; leaves linear-lanceolate or broadly linear, 4-8 cm. long, 

 4-8 mm. wide, acute or gradually acuminate, obtuse to acute 

 at base, reddish brown tinged, glabrescent or appresscd-pilose 

 on both sides, often with sessile discoid glands beneath, sessile 

 or short-petiolate; sheaths 5-13 mm. long, apprcssed-pilose, the 



