BUCKWHEAT FAMILY 63 



stamens 5 ; style 2-cleft ; achene lenticular, oblong-spherical to obovoid, black and shining or 

 slightly granular and dull. 



Borders of lakes and ponds, Boreal and Austral Zones; Alaska to southern California, Quebec, and Penn- 

 sylvania. Type locality: eastern North America. July-Sept. 



29. Polygonum coccineum Muhl. Swamp Persicaria, Swamp Knotweed. 



Fig. 1471. 



Polygonum amphibium var. emersum Michx. Fl. Bor. Amer. 1: 240. 1803. 

 Polygonum coccineum Muhl. ex Willd. Enum. Hort. Ber. 1 : 428. 1809. 

 Polygonum Muhlenbergii S. Wats. Proc. Amer. Acad. 14: 295. 1879. 

 Polygonum emersum Britton, Trans. N.Y. Acad. 8: 73. 1889. 



Stems arising from elongated perennial rootstocks, glabrous or strigose, erect, usually simple, 

 3-10 dm. high. Leaves 6-13 cm. long, ovate-lanceolate to oblong-lanceolate or the upper nar- 

 rowly lanceolate, acute or usually acuminate at apex, rounded or cordate at base, short-petioled, 

 glabrous or frequently strigose-pubescent ; stipule-sheaths cylindric, not ciliate ; racemes 1 or 2, 

 erect, cylindric, 3-10 cm. long; calyx deep rose; stamens and styles exserted; achene lenticular, 

 broadly obovate or orbicular, the sides convex, black and shining. 



In ponds and swamps, Transition and Sonoran Zones; British Columbia to southern California and east 

 to the Atlantic Coast. Type locality: Pennsylvania. Persicaria alismaefolia, P. Covillei, P. Cusicka.P. francis- 

 cana, P. hesperia, P. pratinocola Greene, Leaflets Bot. Obs. 1 : 36-44, 1904, are synonymous. June-Oct. 



30. Polygonum hydropiperoides Michx. Mild Water Pepper. Fig. 1472. 



Polygonum hydropiperoides Michx. Fl. Bor. Amer. 1 : 239. 1803. 



Polygonum hydropiperoides var. strigosum Small, Bull. Torrey Club 19: 355. 1892. 



Polygonum hydropiperoides var. asperifolium Stanford, Rhodora 28: 27. 1926. 



Perennial with glabrous or strigulose stems, 3-10 dm. high. Leaves linear-lanceolate to 

 oblong-lanceolate, 5-15 cm. long, short-petioled, short-ciliate on the margins, and rather sparsely 

 pubescent with appressed hairs on the midrib beneath ; stipule-sheath cylindric, rather coarsely 

 strigose and fringed with bristles ; racemes in terminal panicles, very slender, and more or less 

 interrupted, 3-8 cm. long; calyx white to rose; stamens 8; styles short, 3-parted to below the 

 middle ; achene 3-angled, ovoid or oblong-ovoid, 2 mm, long, smooth and shining. 



Swamps and edges of pools, Transition and Sonoran Zones; northern California south to Mexico and east to 

 Minnesota, Maine, and Florida. Type locality: Pennsylvania. June-Oct. 



31. Polygonum Hydropiper L. Common Smartweed or Water Pepper. 



Fig. 1473. 



Polygonum Hydropiper L. Sp. PI. 361. 1753. 



Polygonum Hydropiper var. projectum Stanford, Rhodora 29: 86. 1927. 



Annual, the stems erect or assurgent, 2-6 dm. high, simple or branched throughout, glabrous. 

 Leaves ovate-lanceolate to narrowly lanceolate, 2-9 cm. long, acute or acuminate at apex, nar- 

 rowed at base to a short petiole, ciliate, sparsely strigose on the midrib beneath, papillose and 

 punctate, very acrid ; stipule-sheaths cylindric, sparsely and coarsely strigose, and sparsely ciliate 

 with rather stiff bristles; spikes paniculate, slender, nodding; sepals glandular-punctate, greenish 

 with white or pale rose margins; stamens 6; styles 2-3-parted; achene lenticular or 3-angled, 

 minutely striated and dull. 



Wet bottom lands and swamps, Transition and Upper Sonoran Zones; Washington and Idaho south to central 

 California, east to the Atlantic States; probably introduced. Type locality: Europe. July-Oct. 



32. Polygonum punctatum Elliott. Water Smartweed. Fig. 1474. 



Polygonum acre H.B.K. Nov. Gen. & Sp. 2: 179. 1817. Not Lam. 1778. 

 Polygonum punctatum Ell. Bot. S. C. and Ga. 1: 445. 1817. 



Perennial, the stems rooting at the decumbent base, erect or ascending, 3-10 dm. high, simple 

 or branched, nearly or quite glabrous. Leaves lanceolate to linear-lanceolate, 5—15 cm. long, 

 acuminate, punctate, ciliate on the margins and often strigose on the midrib; stipule-sheaths 

 strigose or glabrous, conspicuously bristly ciliate; racemes forming a naked or leafy panicle, 

 narrowly linear. 1 . 5-6 cm. long, loosely flowered or interrupted below ; calyx greenish, con- 

 spicuously glandular-punctate ; stamens 8 ; style short, 2-3-parted to the base ; achene lenticular 

 or 3-angled, 2.5 mm. long, black, smooth and shining. 



Moist bottom lands and edges of swamps, Transition and Sonoran Zones; Washington to California across 

 the continent and south to tropical America. Type locality : southern Atlantic States. Aug.-Oct. 



Polygonum punctatum var. leptostachyum (Meisn.) Small, Bull. Torrey Club 19: 356. 1892. Often 

 flowering as an annual, the stems erect, 3-4 dm. high, slender. Leaves lanceolate, 3-8 cm. long, thinner and 

 paler green; racemes very slender, loosely interrupted below. About the same range as the species and possibly 

 specifically distinct, but interbreeding is evident in some localities. 



33. Polygonum Persicaria L. Lady's Thumb, Spotted Persicaria. Fig. 1475. 



Polygonum Persicaria L. Sp. PI. 361. 1753. 

 Persicaria Persicaria Small, Fl. S.E. U.S. 378. 1903. 



Annual, glabrous or sparingly puberulent, the stems erect, usually branched from the base, 

 2-6 dm. high. Leaves lanceolate to linear-lanceolate, acuminate at apex, narrowed to the base, 



