238 POLYGONACEAE 



raceme ovoid, less than 2 cm. long; perianth mostly white; achenes smooth and 

 shining. Polygonum Bistorta linearifolium S. Wats. B. jejuna Greene. Alpine 

 swamps: Mont. Colo. Utah Nev. Alp. Mont. Je-Au. 



3. B. vivipara (L.) S. F. Gray. Blades of the basal leaves oblong or lance- 

 olate, 2-10 cm. long, 1-2.5 cm. wide; stem-leaves lanceolate to linear; raceme 

 narrowly cylindric, 2-10 cm. long, 0.5-1 cm. thick; perianth pale rose-colored 

 or white; achenes dark brown, granular and dull. Polygonum viviparum L. 

 B. scopulina Greene. Alpine, arctic, and subarctic swamps: Greenl. -N.H. 

 N.M. Alaska; Eurasia. Alp. Mont. Je-Au. 



12. FAGOPYRUM (Tourn.) Mill. BUCKWHEAT. 



Caulescent glabrous annuals. Leaves alternate, petioled; blades hastate or 

 cordate; ocreae oblique, entire. Flowers perfect, several in corymbiform cymes, 

 with slender pedicels subtended by an ocreola. Calyx corolloid ; sepals 5. equal. 

 Stamens 8. Styles 3; stigmas capitate. Achenes 3-angled, margined or crested. 

 Embryo S-shaped, central. 



1. F. Fagopyrum (L.) Karst. Stem 1-9 dm. high, branched, pubescent at 

 the nodes; leaf -blades hastate, 2.5-8 cm. long; ocreae fugacious; perianth whit- 

 ish; achenes ovoid, 5 mm. long, with pinnately striate faces, acute-angled. F. 

 esculentum Moench. Escaped from cultivation; native of Eurasia. 



13. ACONOGONUM Reichenb. 



Caulescent herbaceous or rarely suffrutescent plants, with horizontal root- 

 stocks. Leaves fleshy or thin. Inflorescence of axillary and terminal racemes 

 or panicles. Ocreae funnelform, oblique. Pedicels articulate below the peri- 

 anth. Perianth 5-parted, not glandular-punctate. Stamens 5-8, included. 

 Style 3-parted; achenes 3-angled, smooth. Endosperm horny; cotyledons ac- 

 rumbent. 



1. A. phytolaccaefolium (Meisn.) Small. Perennial; stem erect, 1-2 m. 

 high, channeled, branched; leaf -blades lanceolate, 5-15 cm. long, 1-4 cm. wide, 

 acute or acuminate at both ends, slightly crisped, ciliate on the margins; inflo- 

 rescence paniculate, leafy; perianth greenish or whitish, 3 mm. long; segments 

 obovate or oblong, rounded; achenes 4 mm. long, broadly ovoid or oval, light 

 chestnut-colored, shining. Polygonum polymorphum and P. alpinum Am. auth. 

 Subalpine and alpine regions : Alaska Ida. Nev. Calif.; Asia. Submont. Jl-S. 



14. TRACAULON Raf. TEAR-THUMB. 



Annual or rarely perennial, prickly-armed herbs, with weak 4-angled stems. 

 Leaves alternate; blades hastate or cordate, membranous, the petioles and 

 veins prickly. Ocreae oblique. Flowers in terminal or axillary spikes, or capi- 

 tate clusters. Sepals 4 or 5, somewhat colored, neither keeled nor winged. 

 Stamens 5-8; filaments not dilated. Ovary 1-celled; styles 2 or 3, partially 

 united. Achenes lenticular or 3-angled, smooth and shining. Endosperm 

 horny; cotyledons accumbent. 



1. T. sagittatum (L.) Small. Annual; stem slender, decumbent or re- 

 clining, 3-15 dm. high, branched, 4-angled, armed on the angles with sharp re- 

 curved prickles; leaves lanceolate or oblong, sagittate at the base, 1-12 cm. long, 

 0.5-3 cm. broad, the lower petioled, the uppermost sessile; perianth white, green, 

 or red, 4 mm. long, 5-parted; achenes 3-angled, black or brownish. Polygonum 

 sagittatum L. Wet meadows: Newf. Fla. Tex. Sask. Plain. Jl-S. 



16. BILDERDYKIA Dum. FALSE BUCKWHEAT, BINDWEED. 



Annual or perennial twining herbaceous vines. Leaves alternate, with 

 cordate or hastate blades. Ocreae oblique, naked or fringed. Racemes loosely 

 flowered, terminal or axillary, often paniculate. Sepals 5, green, white, or yel- 

 lowish, the outer two sepals and the intermediate one keeled or winged. Pedi- 

 cels slender, reflexed and articulate. Stamens 8; filaments short, converging. 

 Ovary 1-celled; styles 3, short or almost wanting; stigmas capitate. Achenes 



