Genus 5. 



BUCKWHEAT FAMILY. 



661 



3. Polygonum leptocarpum Robinson. Narrow- 

 pointed Knotweed. Fig. 1617. 



Polygonum leptocarpum Robinson, Proc. Bost. Soc. Nat. 

 Hist. 31 : 263. 1904. 



Annual, glabrous, stem very slender, copiously branched, 

 about i° tall, nearly terete, the branches angled. Leaves 

 various, the lower ones early deciduous the upper ones 

 linear-lanceolate to linear, 3"-4" long, acute, pale green ; 

 ocreae becoming very finely lacerate, brown or reddish- 

 brown at the base; flowers sessile or nearly so; sepals 

 4 or 5, green and with whitish or reddish margins; 

 stamens 4 or 5, included ; style 3-parted ; achene slender, 

 3-angled, lanceolate, less than ii" long, curved at the 

 apex. 



Kansas. Sept.-Oct. 



4. Polygonum exsertum Small. Long- 

 fruited Knotweed. Fig. 161 8. 



P. exsertum Small, Bull. Torr. Club 21 : 172. 1894. 



Annual, glabrous, sometimes slightly glaucous, 

 stem slender, brownish, erect or nearly so, con- 

 spicuously striate, branched, i4°-3° tall. Leaves lan- 

 ceolate, rarely oblanceolate, i'-ll' long, acute or 

 cuspidate at the apex, acuminate at the base, nearly 

 sessile ; ocreae soon lacerate, silvery, becoming brown- 

 ish ; sepals 6, greenish, with white margins ; stamens 

 5 or 6, included; achene stout, 3-angled, 2£"-3" long, 

 more or less constricted above the middle, chestnut- 

 brown, smooth, shining, 2-3 times as long as the 

 calyx, at length twisted. 



In brackish marshes, New Brunswick to New Jersey; 

 and on prairies and sand bars, Saskatchewan to Illinois 

 and Nebraska. Aug.-Oct. This is considered by some. a 

 " semiviviparous '" 



state of P. ramosissimum. 



5. Polygonum aviculare L. Knot-grass. 

 Door-weed. Pink-weed. Fig. 1619. 



Polygonum aviculare L. Sp. PI. 362. 1753. 

 P. monspeliense Pers. Syn. 1 : 439. 1805. 



Annual, pale green or bluish green, stem low 

 or ascending, simple or branched, 4-2° long. 

 Leaves broad, oblong to obovate-oblong, i3"-2o" 

 long, short-petioled, narrowed at the base, usually 

 acute at the apex or sometimes obtuse; ocreae 

 silvery, at length lacerate; clusters 1-5-flowered ; 

 flowers relatively large, pedicelled ; sepals 5, green, 

 except the white, pink or purplish borders, i"-ii" 

 long; stamens 5-8; achene 3-angled, ovoid, l£"-2" 

 long, acute, striate-reticulated. 



A weed in cultiyated and waste grounds, common 

 almost throughout North America, Asia and Europe. 

 Bird-, beggar-, stone- or wire-weed. Door-, wire-, 

 way- or crab-grass. Cow-, goose-, swine- or bird- 

 grass. Bird's knot-grass. Bird's- or sparrow-tongue. 

 Ninety-knot. June-Oct. 



