54 POLYGONACEAE 



11. Rumex paucifolius Nutt. Alpine Sheep Sorrel. Fig. 1440. 



Rumex paucifolius Nutt. Journ. Acad. Phila. 7: 49. 1834. 



Rumex Engelmannii var. Geyeri Meissn. in DC. Prod. 14: 64. 1856. 



Rumex Geyeri Trelease, Rep. Mo. Bot. Gard. 3: 78. 1892. 



Rumex paucifolius var. gracilescens Rech. f. Field Mus. Bot. Ser. 17: 27. 1937. 



Perennial from a stout simple or branched taproot, the stems 2-7 dm. high. Leaves mostly 

 basal, linear to oblong-lanceolate, 4—10 cm. long, entire, narrowed to petioles of about the same 

 length to twice as long; panicles naked; flowers becoming reddish; valves 2.5-3 mm. long, 

 suborbicular, cordate, finely veined, without grains ; achenes smooth, 1 mm. long. 



Mountain meadows and streams, Boreal Zones; British Columbia and Alberta south to Colorado, Utah, and 

 the Sierra Nevada, California. Type locality: "Near Flat-Head River.' June-Sept. 



12. Rumex Acetosella L. Sheep Sorrel. Fig. 1441. 



Rumex Acetosella L. Sp. PI. 338. 1753. 



Dioecious perennial by slender running rootstocks, the stems slender, erect or decumbent at 

 base simple or branched, 2-4 dm. high, glabrous. Leaves narrowly hastate, 2.5-8 cm. long the 

 uppermost subentire ; petioles of the lower leaves often longer than the blades ; panicles naked, 

 narrow, turning red in age ; calyx 1 mm. long, green ; stamens exserted ; valves scarcely equaling 

 the granular achene. 



Open grassy slopes and fields, Upper Sonoran to Boreal Zones; widely introduced in the Pacific States, native 

 of Europe. The foliage acid. Feb.-Sept. 



11. OXYRIA Hill, Veg. Syst. 10: 24. 1765. 



Low glabrous perennial, with a thick chaffy rootstock, erect stems and acrid juice. 

 Leaves mostly basal, long-petioled, rounded or reniform, their stipule-sheaths cylindric. 

 Flowers perfect, small, green, verticillate, the verticils arranged in terminal pamcled 

 racemes. Sepals 4, the outer larger than the inner. Stamens 6, included ; filaments sub- 

 ulate. Ovary 1-celled; style short, 2-parted; stigmas fimbriate, persistent; achene len- 

 ticular, the body ovate with two broad wings. [Greek, meaning sour, in reference to the 

 acid juice of the leaves.] 



Two species, the following which is the generic type, the other Himalayan. 



1. Oxyria digyna (L.) Hill. Mountain Sorrel. Fig. 1442. 



Rumex digynus L. Sp. PI. 337. 1753. 

 Oxyria digyna Hill, Hort. Kew. 158. 1768. 



Stems usually several from a stout chaffy rootstock, scape-like, simple or few-branched, 

 5-25 cm. high. Leaves mostly basal, reniform or orbicular-reniform, 15-35 mm. wide, undulate; 

 stipule-sheaths loose, oblique; racemes many-flowered; pedicels slender, recurved; sepals red or 

 greenish, 1.5-2 mm. long, the inner erect in fruit and 4-6 mm. long, the outer reflexed; achene 

 with broad membranous wings. 



Among rocks, Arctic- Alpine and Hudsonian Zones; Alaska to Greenland, south in the Pacific States to San 

 Bernardino Mountains, California, in the Rocky Mountains to New Mexico, and in the east to the White Moun- 

 tains, New Hampshire; also boreal and alpine Europe and Asia. Type locality: in Europe. July-bept. 



12. POLYGONUM [Tourn.] L. Sp. PI. 359. 1753. 



Annual or perennial terrestrial or aquatic herbs, or sometimes shrubby, usually with 

 swollen joints. Stipules united into a prominent sheath or sometimes obsolete. Leaves 

 alternate, entire, the petioles often articulate with the ocreae. Flowers mostly perfect, 

 axillary or racemose on jointed pedicels. Calyx 5-parted or sometimes 6-parted, often 

 petaloid, similar and erect in fruit. Stamens 3-9, but usually 5 ; filaments often dilated. 

 Styles or stigmas 2 or 3. Achenes 3-angled, or lenticular, enclosed by the persistent calyx. 

 Embryo slender curved around one side of the endosperm; cotyledons incumbent or 

 accumbent. [Name Greek, meaning many knees in reference to the jointed stems.] 



About 200 species of wide geographical distribution. Type species, Polygonum aviculare L. 



Plants not twining; outer sepals not winged or keeled (see P. cuspidatum and P. sachalinense) . 



Stipule-sheaths, at least at length deeply lacerate, mostly 2-lobed; leaves small; flowers in 1- to few-flowered 

 axillary clusters, scattered or in leafy-bracted spikes or racemes; cotyledons incumbent. 

 Leaves articulate with the sheath, 1-nerved; flowers 2 or more rarely solitary in the axils; short-pedicelled. 



I. AVICULARIA. 



Leaves not articulate, narrow and acicular, 3-nerved, the two lateral marginal; flowers solitary in the 

 axils; sessile. II- Duvaria. 



Stipule-sheaths not 2-lobed nor lacerate; flowers in racemes or spikes terminating the branches, not leafy- 

 bracted; cotyledons accumbent. 

 Stems simple, from fleshy rootstocks; basal leaves long-petioled, the cauline short-petioled or sessile; 



raceme solitary, terminal. HI- Bistorta. 



Stems branched; leaves all cauline and similar; racemes terminating the branches. 



Sheaths funnelform, oblique and more or less open on the side facing the leaf, naked at apex. 



IV. Aconogonum. 



Sheaths cylindric, truncate, naked or ciliate-fringed at apex. V. Persicaria. 



Plants herbaceous twining vines; leaves cordate to hastate at base; outer calyx-lobes keeled or winged. 



VI. BlLDERDYKIA. 



