320 POLYGONACE^E. (BUCKWHEAT FAMILY.) 



sheaths often somewhat hairy or ciliolate : spikes shorter, oblong and blunt. — 

 In the Wahsatch, on the Saskatchewan, and eastward to New York. Rare. 



9. P. nodosum, Pers. Often stout, 1 to 4 feet high, branching, mostly gla- 

 brous, often sparingly and minutely glandular on the peduncles : leaves rather 

 narrowly lanceolate, cuneate at base and shortly petioled, somewhat scabrous 

 with short prickly hairs on the midrib and margins : spikes axillary and termi- 

 nal, oblong and erect or often linear and nodding : flowers white or light rose- 

 color: stamens 6 and styles 2, included. — Colorado and New Mexico to 

 Arizona, California, and Oregon. 



10. P. amphibium, L. Aquatic, stout and glabrous or nearly so, not 

 branching above the rooting base : leaves floating, thick, smooth and shining 

 above, usually long-petioled, elliptical to lanceolate, cuneate or cordate at base : 

 sheaths leaf-bearing at about the middle : spike terminal, dense, ovate or oblong, 

 \ to 1 inch long, on a usually short peduncle : flowers bright rose-color : the 

 5 stamens and 2-cleft style exserted. — From the Sierra Nevada eastward across 

 the continent. In shallow water or on muddy banks the stems become erect, 

 the petioles shorter, and the whole plant more strigose-pubescent. 



11. P. Muhlenbergii, Watson. In muddy or dry places, scabrous irilh 

 short appressed or glandular hairs, especially upon the leaves and upper part 

 of the simple stem : leaves thinner and longer, rather broadly lanceolate, nar- 

 rowly acuminate, usually rounded or cordate at base : spikes more elongated, 

 3 inches long, often in pairs : flowers and fruit nearly as in the last. — P. am- 

 phibium, var. terrestre, of Gray's Manual. Across the continent. 



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



margined. 



12. P. Hartwrightii, Gray. Closely allied to the two preceding speriss, 

 growing usually in the mud, the ascending stems rooting at the base and 

 very leafy, more or less rough hairy, at least on the sheaths and bracts : leaves 

 rather narrow, on very short petioles, not punctate, adnate to the middle of the 

 sheath : flowers bright rose-color: sepals not glandular-dotted : style 2-cleft, and 

 akcne somewhat fattened. — Proc. Am. Acad. viii. 294. From California and 

 Utah eastward through the Northern States. 



13. P. Hydropiper, L.. Smooth, 1 to 2 feet high, juice very acrid: 

 leaves punctate : spikes nodding, usually short or interrupted : flowers mostly 

 greenish: sepals conspicuously dotted: stamens 6: style 2 to 3-parted: akene 

 dull, minutely striate, either flat or obtusely triangular. — Ranging across the 

 continent northward, where it is probably indigenous. 



§ 3. Glabrous alpine or subalpine herbs, with thick creeping rootstocks and simple 

 stems : flowers in dense spike-like racemes : leaves not jointed on the petiole : 

 sheaths obliquely truncate, naked, as well as the scarious ovate or lanceolate 

 bracts: perianth colored, deeply 5-cieft, at length appressed to the trianqular 

 akene: stamens 8, with filiform filaments: styles 3, long. — Bistorta. 



14. P. Bistorta, L. Stems a foot or two high: leaves few, the radical 

 ones on long petioles, oblong-lanceolate to linear, acute at each end, the cau- 

 line much reduced, mostly obtuse at base and sessile upon the sheath, the 

 margin often slightly revolute : flowers rose-colored to white, on slender pedi- 

 cels, in very dense ovate to oblong spikes and usually long-pedunculate : stamens 



