POLYGONACEAE 405 



leaves long-petioled, oblong, ovate, or broadly so, 15-20 cm. nipponicus (Fr. & Sav.) Nakai; R. dentatus subsp. nipponictis 



long, 8-12 cm. wide, obtuse to acute, cordate; inflorescence (Fr. & Sav.) Rechinger f. Ko-gishi-cishi. Smooth peren- 



leafy, with ascending branches; outer sepals spreading, about nial herb; branches ascending to nearly spreading; lower 



1.5 mm. long, the inner narrowly deltoid-ovate or ovate-orbicu- leaves oblong-lanceolate to lanceolate, obtuse, rounded at base, 



lar, subacute, 4-6 mm. long, 3-5 mm. wide, with rather long-pctioled, 4-6 cm. long, 1-2 cm. wide; inflorescence leafy, 



prominent netted veinlets, short-spined or toothed on margin, the verticils widely separated, the outer sepals ascending, 



the tubercles ovoid, 1.5-2 mm. long; achenes dark brown, the inner deltoid-ovate, 4-5 mm. long, 2-3 mm. wide, with 



ovate, acutely 3-angled, lustrous, about 2.5 mm. long. few marginal spines about 2 mm. long; achenes similar to 



June-Sept. Hokkaido, Honshu; very variable. Eurasia and the preceding. May-June. Lowlands; Honshu (Kanto 



N. Africa. Distr. and westw.), Shikoku, Kyushu. China and Korea. 



14. Rumex nipponicus Fr. & Sav. R. obtusijolius var. 



2. OXYRIA Hill Maruba-gishi-gishi Zoku 



Low glabrous perennial herbs; radical leaves long-perioled, reniform-orbicular, entire, the margin undulate, the stipules 

 scarious; scapes arising from short stout rhizomes, erect, naked or 1-leaved; inflorescence paniculate, the flowers few at each 

 node, small, bise.xual, the pedicels jointed at apex; perianth-segments or sepals 4, in 2 series, the outer whorl reflexed in fruit, 

 the inner whorl slightly accrescent after anthesis, appressed to the achene; stamens 6; ovary compressed; styles 2, the stigma 



broad, fimbriate; achenes flat, winged on margin; embryo lateral. Two species in tlie arctic and alpine regions of the N. 



Hemisphere. 



1. Oxyria digyna (L.) Hill. Rumex digynus L.; O. reni- long, the branches erect; inner sepal-lobes spathulate-obovate, 



formis Hook. Maruba-gishi-gishi, Jin'yo-suiba. Glabrous, about 2 mm. long, rounded at apex, membranous; achenes 



sometimes slightly reddish perennial herb from stout rhi- ovate, flat, about 2 mm. long, with a membranous wing on 



zomes; scapes 10-30 cm. long, naked or with a small sub- margin, orbicular-cordate, retuse. July-Aug. Wet barren 



tending leaf below the inflorescence; leaves succulent, some- alpine slopes; Hokkaido, Honshu (centr. distr.); rare. 



what tufted, long-petioled, reniform-orbicular, rounded to sub- Arctic and alpine regions of the N. Hemisphere, 

 retuse, 1.5-2.5 cm. long, 2-4 cm. wide; inflorescence 4-10 cm. 



3. POLYGONUM L. Tade Zoku 



Herbs, rarely subshrubs, often scandent; leaves alternate, with a sheathlike membranous stipule (ochrea) at base; flowers in 

 fascicles or solitary, more often in spiciform panicles (spikes), racemes or panicles, the pedicels jointed; perianth-segments usually 

 5, 2-seriate, one of the whorls sometimes accrescent after anthesis; ovary lenticular or trigonous; styles 2 or 3, free or connate at base, 



the stigma capitellate or rarely fimbriate; fruit enclosed within the persistent perianth; embryo curved. About 200 species, 



cosmopolitan, especially abundant in the N. Hemisphere. 



I A. Styles hooked at apex, persistent, firm; perianth-segments 4 I. P. filiforme 



IB. Style not hooked, deciduous, not hardened; perianth-segments 5, rarely 4. 



2A. Flowers fasciculate in leaf-axils, not forming a spike or raceme; leaves small, linear to oblong, entire. 



3A. Leaf-sheath nerveless or with short nerves near base; leaves with obsolete lateral nerves; achenes smooth, lustrous. 



2. P. plebeitim 

 3B. Leaf-sheath nerved except at apex; leaves with more or less raised lateral nerves at least beneath; achenes punctulate and scarcely 

 lustrous. 



4A. Achenes exserted; plant glaucescent, becoming dark brown when dried 3. P. polynetiron 



4B. Achenes scarcely exserted; plant green, scarcely glaucescent, not becoming dark brown when dried 4. P. aviculare 



2B. Flowers in spikes or racemes, except sometimes in Nos. 44-46. 



5A. Stems scaposc, simple; radical leaves conspicuous; rhizomes thickened. 

 6A. Spike solitary, always terminal. 



7A. Stem-leaves I or 2, small, or none 5. P. tcnuicauU 



7B. Stem-leaves usually more than 2, foliaceous. 



8A. Spikes bearing small bulbils on the lower part 6. P. viviparum 



83. Spikes not bearing bulbils. 



9A. Petioles of radical leaves wingless 7. P. hayachincnse 



9B. Petioles of radical leaves winged 8. P. blstorta 



6B. Spikes axillary and terminal 9. P. siiffullum 



5B. Stems leafy, not scapose, often branched; radical leaves not prominent. 

 lOA. Stems with retrorse prickles. 



IIA. Stipules, at least some of them, with a marginal dilated green limb. 

 12A. Leaves deltoid, nearly as long as wide. 

 13A. Stems much elongate, scandent. 



14A. Plant glabrous; leaves peltate; spikes with a rather prominent leaflike orbicular bract at base; perianth becoming 



slightly fleshy and bluish in fruit; achenes black and lustrous 10. P. perloliatum 



14B. Plant loosely puberulous; leaves basifixed; spikes without prominent Icaflike bracts; perianth not becoming fleshy; 

 achenes dull II. P. senticosum 



