

 Polygonum. POLYGONACE^E. 13 



2. Flowers spicate, solitary and sessile in the axils offoliaceous bracts : leaves 

 and bracts not jointed at base, striately 3-nerved ; stipules fimbriate or 

 2-lobed : perianth colored, 5-parted, at length appressed to the triangular 

 akene : stamens 8 ; inner filaments scarcely dilated : styles 3, i)ersistent. 

 Very slender low erect branching annuals, with narrow rigid leaves. 

 DURAVIA, Watson. 



12. P. Californicum, Meisner. Stems 3 to 6 inches high, striate and brownish, 

 glabrous or minutely scabrous : leaves linear to filiform, 6 to 15 lines long, cuspi- 

 date : spikes very slender, elongated, the bracts subulate, 1 or 2 lines long ; stipules 

 sheathing, deeply lacerate-fringed, a line long, nearly equalling the rose-colored 

 flowers : akene narrowly lanceolate, slightly exserted ; styles slightly divergent. 

 DC. Proclr. xiv. 100; Watson, 1. c., the fruit described from immature specimens. 



Central California (Sacramento Valley and in the Sierra Nevada) to the Columbia River (Nuttall), 

 ou dry soil, rather frequent. Two additional members of this section are described on page 479. 



3. Flowers fascicled, in usually dense spikes, with small scarious bracts : leaves 

 not jointed on the petiole, pinnately many-veined: sheaths cylindrical and 

 truncate, scarious, entire, naked or ciliate-f ringed or margined: perianth 

 colored, ^-parted, appressed to the lenticular or triangular akene : stamens 

 4 to 8 ; filaments filiform : stigmas 2 or 3. PERSICARIA, Linn. 



* Sheaths and bracts not ciliate nor fringed : sepals not punctate : style 2-cleft 

 and akene flattened or lenticular. 



13. P. nodosum, Persoon. Annual, often stout, 1 to 4 feet high, branching, 

 mostly glabrous, often sparingly and minutely glandular on the peduncles : leaves 

 rather narrowly lanceolate, attenuate upward from near the base and acuminate, 

 cuneate at base and shortly petioled, somewhat scabrous with short prickly hairs on 

 the midrib and margins : spikes axillary and terminal, oblong and erect or often 

 linear and nodding, an inch long or more : flowers white or light rose-color, a line 

 long or nearly so : stamens 6, and styles 2, included : akene ovate, less than a line 

 broad. Meisuer, 1. c. 118. 



In moist places ; San Jose Valley and Santa Cruz (Brewer) and Alameda County (Kellogg), also 

 in Oregon (Hall) and New Mexico (Fcndler) a form apparently identical with that of Europe 

 and Asia. Farther eastward it has more attenuated spikes and larger leaves, perhaps running into 

 P. incarnatum, Ell. 



P. PENNSYLVANICUM, Linn. A similar species, but the branches above and especially the pe- 

 duncles beset with stipitate glands : flowers larger and bright rose-color, in short erect spikes, 

 often on exserted pedicels : stamens usually 8 : style bifid, exserted : akene nearly orbicular, over 

 a line broad. Common in the Atlantic States and west to Colorado and Sonora (Thurbcr), and 

 to be expected in California, at least as an introduced weed. 



14. P. amphibium, Linn. Perennial, 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 oblong or sometimes lanceolate, acutish or 

 acute, cuneate or cordate at base, 2 to 5 inches long : sheaths leaf-bearing at about 

 the middle : spike terminal, dense, ovate or oblong, a half to an inch long, on a 

 usually short peduncle : flowers bright rose-color, 1| to 3 lines long, the 5 stamens 

 and 2-cleft style exserted : akeiie lenticular, smooth. Meisner, 1. c. 115. 



Perhaps not found west of the Sierra Nevada, but common in fresh waters about Mono Lake 

 and Lake Tahoe, ranging northward to British Columbia, eastward across the continent, and to 

 Mexico ; in the Old World from W. Europe to China. In shallow water or on muddy banks the 

 stems become erect, the petioles shorter, and the whole plant more strigose pubescent. 



15. P. Muhlenbergii, Watson. Perennial, in muddy or dry places, scabrous 

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

 of the simple stem : leaves thinner, rather broadly lanceolate, narrowly acuminate, 

 usually rounded or cordate at base, 4 to 7 inches long : spikes more elongated, 1 to 



