POLYGONACE^E. (BUCKWHEAT FAMILY.) 319 



•*- •*- 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 

 frnit as in P. erection, 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 : flowers 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. microspermum, Engelm. A low slender form, with minute flowers 

 and fruit. 



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



colored: leaves linear. 



5. P. imbricatum, Nntt. 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-f ringed or margined: perianth colored, ^-parted, oppressed to 

 the lenticular or triangular akene: stamens 4 to 8; f laments filiform. — 

 Persicaria. 



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



and akene fattened 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. ilicarnatum, 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: flowers 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 : 



