14 POLYGONACE^E. Polygonum. 



3 inches long, often in pairs : flowers arid fruit nearly as in the last. P. amphibium, 

 var. terrestre, Gray, Manual, 416, and others ; not of Willdenow. P. amphibium, 

 var. (\) Muhlenbergii, Meisner, 1. c. 116. 



In Washington Territory and Oregon, and collected in California (Bloomer) but locality not 

 given extending eastward to the Atlantic Coast and Texas. 



* * Sheaths and. bracts bristly ciliate or the sheaths sometimes foliaceously 



margined. 



Sepals not punctate : style 2-cleft, and akene somewhat flattened. 



16. P. Hartwrightii, Gray. Perennial, closely allied to the two preceding spe- 

 cies, growing usually in mud, the ascending stems rooting at base and very leafy : 

 differing from the form of P. ambiguum, growing in like localities, by being more or 

 less rough-hairy, at least on the sheaths and bracts, the former ciliate and often with 

 abruptly spreading foliaceous borders ; leaves rather narrow, 2 to 7 inches long, on 

 very short petioles, adnate to the middle of the sheath. Proc. Am. Acad. viii. 294. 



Plumas Co. (Mrs. M. E. P. Ames) ; Utah ( Watsvn, Ward) ; and eastward through the North- 

 ern States. It varies greatly in hirsuteness and in the characters of the sheath, and when grow- 

 ing in water the lower leaves are thick, smooth, and floating, approaching P. amphibium too 

 closely. 



P. PEKSICARIA, Linn. Resembling P. nodosum, but sheaths and bracts ciliate ; leaves usually 

 marked by a dark spot near the middle ; spikes short, erect ; flowers shortly pedicelled ; style 

 2 - 3-cleft, and akene sometimes triangular. A very common species in the Atlantic States, in- 

 troduced from Europe ; reported from California only in Bot. Beechey. 



i Sepals conspicuously dotted and leaves punctate : style mostly 3-parted, and 

 akene triangular : juice very acrid. 



17. P. acre, HBK. Perennial, rooting and decumbent at base, 2 to 5 feet high, 

 branching, smooth or somewhat scabrous with short appressed hairs : leaves lanceo- 

 late to linear-lanceolate, acuminate, attenuate to a very short petiole : sheaths and 

 the short bracts bristly ciliate : spikes loose and filiform, 1 to 3 inches long, erect 

 on long peduncles : flowers greenish white or purplish, a line long : stamens 8. 

 Nov. Gen. ii. 179; Gray, Manual, 416. 



Common in the Atlantic States and ranging to Mexico and South America ; collected in the 

 San Jose Valley (Brewer), but perhaps introduced. 



P. HYDKOPIPEK, Linn., is an allied annual species, with shorter acute or often obtuse leaves 

 and more nodding spikes ; stamens 6 ; style more frequently 2-parted, and akene consequently 

 often compressed. A European species which also ranges across this continent northward ; found 

 in Washington Territory and perhaps in Northern California. 



4. Glabrous alpine or subalpine herbaceous perennials, with thick creeping root- 

 stocks and simple stems : flowers in dense spike-like racemes ; perianth 

 colored, deeply 5-c left, at length appressed to the triangular akene: stamens 

 8, with filiform filaments : styles 3, long : leaves pinnately veined ; petioles 

 not jointed: sheaths obliquely truncate, naked, as well as the scarious ovate 

 or lanceolate bracts. BISTORTA, Linn. 



1 8. P. Bistorta, Linn. Stems usually a foot or two high : leaves few, the 

 radical ones on long petioles, oblong-lanceolate to linear, acute at each end, 2 to 8 

 inches long, the cauline much reduced, mostly obtuse at base and sessile upon the 

 sheath; the margin often slightly revolute : sheaths elongated: flowers 1^ to 2 

 lines long, rose-colored to white, on slender pedicels, in very dense ovate to oblong 

 8: dkes i to 1| inches long and usually long-pedunculate : bracts ovate, acuminate : 

 stamens and styles exserted : akene 1 lines long, smooth and shining. Meisner, 

 DC. Prodr. xiv. 125. 



Throughout the northern hemisphere ; frequent in meadows and on stream-banks in the Sierra 

 Nevada at 6 -10,000 feet altitude. 



