POLYGON ACE^J. (BUCKWHEAT FAMILY.) 319 



- -t- Branches slender and virgate, angled, terminating in more or less open spikes, 

 the narrow leaves diminishing upward and becoming bract-like. 



3. P. ramosissimum, Michx. Erect or ascending, usually 2 to 4 feet 

 high, often branching only above, glabrous, the whole plant yellowish ; sheaths 

 loose, becoming lacerate to the base : leaves lanceolate to linear : flowers and 

 fruit as in P. erectum, the sepals more frequently 6, stamens 3 to 6, and akene 

 usually smooth and shining. From the Sierra Nevada eastward across the 

 continent. 



4. P. tenue, Michx. Erect and slender, to \\feet high, glabrous and 

 somewhat glaucous, sometimes slightly scabrous at the nodes : sheaths with a close 

 somewhat herbaceous base, sparingly scarious and lacerate above : leaves linear to 

 lanceolate, usually much reduced above : jlowers often solitary and usually dis- 

 tant, soon reflexed, the sepals margined with white or rose-color : stamens 8 : 

 akenes ovate, black and shining. From Arizona to British Columbia and 

 eastward across the continent. The following varieties occur in the Rocky 

 Mountains : 



Var. latifolium, Engelm. With broader leaves and more numerous 

 flowers. 



Var. microspermuni, Engelm. A low slender form, with minute flowers 

 and fruit. 



* * Low and slender : Jlowers in short dense spikes, with imbricated bracts : sepals 



colored: leaves linear. 



5. P. imbricatum, Nutt. Stem 1 to 8 inches high, smooth or slightly 

 scabrous at the nodes, often diffusely branched : sheaths rather large, 2-parted 

 or lacerate above the short scarious base : bracts with sometimes a scarious 

 margin : flowers nearly sessile, rose-colored or white : stamens 3 or 5 : akene 

 minutely tuberculate-striate or smoothish. Alpine and subalpine, from Colo- 

 rado to California and Oregon. It has usually been referred to P. coarctatum. 



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

 not jointed on the petiole: sheaths cylindrical and truncate, scarious, entire, 

 naked or ciliate-fringed or margined: perianth colored, 5-parted, appressed to 

 the lenticular or triangular akene : stamens 4 to 8; filaments filiform. 

 PERSICARIA. 



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



and akene flattened or lenticular. 



6. P. Pennsylvanicum, L. Stem 1 to 3 feet high, smooth below, the 

 branches above and especially the peduncles beset with bristly -stalked glands: 

 leaves lanceolate, roughish on the midrib and margins : spikes oblong, obtuse, 

 erect, thick : flowers bright rose-color : stamens mostly 8, somewhat exserted. 

 Colorado and eastward to the Atlantic States. 



7. P. incarnatum, Ell. Stem 3 to 6 feet high, nearly glabrous, the pedun- 

 cles, etc. often minutely rough with scattered sessile glands : leaves rough on 

 the margins and midrib, elongated-lanceolate : spikes linear, nodding, becoming 

 slender: Jlowers smaller than in the last, lighter rose-color shading to white: 

 stamens 6 and styles 2, both included. Colorado and eastward to the Atlantic 

 States. 



8. P. lapathifolium, Ait., var. incanum, Koch. Lower, with shorter 

 and less pointed leaves, which are lanceolate, obtuse, and white-downy beneath : 



