the Wse, scarcely 0.5 mm. long; achene triquetrous black, smooth and shining, 

 usually included, 3-3.5 mm. long, about half as broad. 



In wet meadows, marshes and edge of water in streams and lakes, in N. M. 

 (widespread) and Ariz. (Apache, Coconino and Graham cos.), June-Sept.; 

 throughout most of Can. and U. S. 



11. Polygonum ramosissimum Michx. 



Taprooted annual (in some situations the taproot becoming ligneous and as 

 much as 1 cm. thick late in the season), rather variable in habit but (except in 

 injured specimens) having only one ascending or usually erect mainstem near 

 ground level, the whole plant (2-) 3-12 dm. tall and usually with numerous ascend- 

 ing or erect branches; leaf blades of midstem lanceolate or linear, (4-) 7-22 mm. 

 long, green, flat, without conspicuous nervation, either persistent or falling, upper- 

 most (bracteal) leaves with smaller blades, persistent or falling; flowers solitary 

 or in 2's or 3's at the nodes of the upper 1-2 cm. of the stem and branches, not 

 crowded; pedicels filiform, at least some of them on the plant at fruiting time 

 long enough to bend over (i.e., exserted from ocreae) so that the yellowish-green 

 fruiting calyx (which completely covers the achene) is drooping; sepals nearly 

 always 6 (very rarely 5); achenes mahogany-colored, equilaterally trigonous, 

 sharp-angled, mildly striate to smooth, usually shiny and 2-3 mm. long. 



In marshes, edge of streams, ponds and lakes, in seasonally wet areas, wide- 

 spread in Tex., Okla. (Waterfall), N. M. and Ariz. (Coconino, Apache and 

 Yavapai cos.), summer-fall; most of e. U.S. s. to Del., Pa., O., Ind., 111., Mo., 

 Okla., Tex., N.M. and Ariz. 



12. Polygonum viviparum L. 



Perennial from a short thick erect or ascending rootstock, with 1 to several 

 flowering stems mostly 1.5-3 dm. tall; leaves mostly basal, long-petiolate, not 

 jointed to the stem, narrowly oblong to narrowly oblong-lanceolate, 3-8 cm. long; 

 stipules brown, strongly sheathing, 2-5 cm. long, oblique at tip, not lacerate; 

 cauline leaves 2 to 4, much narrower than basal leaves, reduced upward and 

 becoming sessile; inflorescence a single terminal spikelike raceme usually 4-8 cm. 

 long and 1-1.5 cm. thick; bracts (especially lower ones) somewhat remote and 

 with the flowers replaced by small pinkish to purplish bulblets, the normal flowers 

 of the upper small membranous bracts with pedicels 2-4 mm. long; perianth 3-3.5 

 mm. long, connate and usually greenish for one fourth to one third of the length, 

 the 5 segments oblong and white to pink; flowers usually functionally imperfect, 

 the stamens 8 when developed and usually exserted, the filaments equalling to 

 twice as long as the perianth; in the pistillate flowers the stamens usually more or 

 less rudimentary and shorter than the perianth; styles 3, distinct nearly to the 

 base, 3-4 mm. long; achenes triquetrous, usually not developing, normally dark- 

 brown, smooth and shining, 2-3 mm. long. Bistorta vivipara (L.) S. F. Gray. 



In wet meadows, in mud and seepage about lakes and on stream banks, and 

 shaded woodlands, in N. M. (Colfax, Santa Fe, San Miguel and Taos cos.), and 

 possibly Ariz., May-Sept.; Greenl. to Alas., s. to N. E., Minn., N.M., (?) Ariz. 

 and Wash. 



13. Polygonum bistortoides Pursh. Snakeweed. Fig. 406. 



Perennial from a short thick erect or ascending rhizome, with 1 or more simple 

 erect flowering stems 2-6 dm. tall; leaves mostly basal, long-petiolate. not jointed 

 to stem, elliptic to oblong-lanceolate or oblanceolate, to about 1.5 dm. long, 

 rounded to cuneate at base; stipules brownish, oblique, not lacerate, 3-6 cm. long; 

 cauline leaves few, noticeably reduced upward, all but the lowest sessile, lanceo- 

 late, semicordate at base; racemes terminal, spikelike, many-flowered, mostly 2-4 



817 



