BUCKWHEAT FAMILY. 

 36. Polygonum Zuccarinii Small. Japanese Knotweed. 



Polygonum cuspidaium Sieb. & Zucc. Fl. Jap Fain 



Nat. 2: 84. 1846. Not Willd. 1825. 

 Polygonum Zttintn'iiii Small, Mem. Dent. Bot. Col 



Coll. i: 158. pi. 66. 1895. 



Perennial, glabrous, more or less scurfy, stem 

 stout, erect, woody below, terete or slightly 

 angled, much branched, 4-8 tall. Leaves ob- 

 long-ovate or ovate-lanceolate, petioled, 2 / -6 / 

 long, acuminate-cuspidate at the apex, truncate 

 or subcordate at the base, reticulate-veined on 

 both surfaces, their margins undulate; ocreae 

 oblique, smooth, fugacious; racemes mostly ter- 

 minal, panicled, 2 / -4 / long, or axillary, many- 

 flowered, more or less pubescent; flowers green- 

 ish-white, long-pedicelled; outer segments of the 

 5-parted calyx very broadly winged in fruit; 

 stamens 8; style 3-parted; achene 3-angled, nar- 

 rowly oblong or oblong-pyramidal, i%"-\W 

 long, black, smooth, shining. 



Escaped from cultivation near Philadelphia, Pa., 

 Schenectacly, N. Y., and Atlantic Highlands, N. J. 

 Native of Japan. July-Oct. 



567 



fr I353-) 



Polygonum sagittatum L/. 



Arrow-leaved Tear-thumb. (Fig. 1354.) 



Polygonum sagillalnm L. Sp. PI. 363. 1753. 



Annual, light green, stem slender, weak, de- 

 cumbent, or climbing over other plants by the 

 abundant sharp recurved prickles which arm its 

 4 prominent angles. Leaves lanceolate-sagittate or 

 oblong-sagittate, %'-$' long, obtuse or acute at the 

 apex, slightly rough on the margins, the lower pe- 

 tioled, the upper subsessile; petioles and lower sur- 

 face of the midribs prickly; ocreae oblique, not 

 ciliate, fringed at the base by a few bristle-like 

 prickles; flowers in rather dense terminal heads or 

 racemes; calyx greenish or rose-colored ; stamens 

 usually 8; style 3-parted to below the middle; 

 achene 3-angled, oblong-pyramidal, thick-pointed, 

 i#" long, dark red, smooth, shining. 



In wet soil, Newfoundland and N\.i So>ti.i t tin 

 Northwest Territory, smith to Florida and Kansas. 

 Ascends to 3000 ft. in Virginia. July-Sept. 



38. Polygonum arifolium L,. Halberd- 

 leaved Tear-thumb. (Fig. 1355.) 



Polygonum arifolium L,. Sp. PI. 364. 1753. 



Perennial, stem ridged, redlining, 2-6 long, the 

 ridges armed with recurved prickles. Peduncles 

 and pedicels glandular or pubescent; leaves broadly 

 hastate, long-petioled, t'-io' long, pubescent or 

 glabrous beneath, the apex and basal lobes acumi- 

 nate; petioles and stronger nerves prickly; ocreae 

 oblique, fringed at the summit with short bristles 

 and at the base with slender prickles; flowers in 

 terminal and axillary heads or racemes; calyx rose- 

 color or greenish, 4-parted; stamens 6; style 2-parted. 

 achene lenticular, broadly obovate, 2" long, strongly 

 biconvex, dark brown, smooth, shining. 



In moist or wet soil, New Brunswick and Ontario to 

 Minnesota, south to South Carolina. July-Sept. 



