MEMOIRS OF THE NEW YORK BOTANICAL GARDEX. I29 



It is distinguished from P. Engrhnannii by tiie achenes, which are 

 constricted at both ends, and by the generally broader leaves. 

 Montana: Sweet Grass Canon, Sept., 1896, Flodman, 401. 



* Polygonum Nuttallii Small, Mem. Dep. Bot. Columbia College, 



I : 132 ; Polygon iiin intcrmcdiiun Nuttall ; Wats. Proc. Am. Acad. 



17 : 378 ; not Ehrh. 



In this as in P. spcrgiilariaeformc the flowers are in interrupted 

 racemes at the ends of the branches ; it differs from that species in its 

 ovoid, not oblong, achenes and dilated filaments. 



* Polygonum spergulariaeforme Meisn. ; Small, Bull. Torr. Bot. 



Club, 19: '^^6 [Small, Mon. 130]: Polygonuni coarctatnm 



Dougl. ; Hook. Fl. Bor. Am. 2: 133 [Bot. Cal. 2: 12]; not 

 Willd. 



In sandy soil at an altitude of 1500-2000 m. 



Montana: Sixteen Mile Creek, 1883, Scribncr, 24.2; Mussel- 

 shell River, 1882, Canhy ; Billings, 1898, Williams & Griffith. 



Yellowstone Park: Lake, 1871, Robert Adams (Hayden 

 Surv.) ; 1883, Miss Mary Comptoii. 

 *Polygonum Kelloggii Greene, Fl. Fran. 134 [Small, Mon. 134]. 



Polygonum coarc/atum minus Meisn. in DC. Prod. 14: loi. 



Characterized by the continuous leafy terminal racemes, the 

 annual root and low habit, the stems being only 1-5 cm. long. In 

 sandy soil. 



Yellowstone Park: Yellowstone Lake, 1871, P. Adams. 



* Polygonum polygaloides Meisner, in DC. Prod. 14: loi [Bot. Cal. 



2: 12; Small, Mon. 136]. 



Montana: Beaver Head Co., 1888, Tn'ccdy, 104. and loj. 

 Yellowstone Park : 1884, Tweedy, 26. 

 Polygonum Watsonii Small, Mem. Dep. Bot. Columbia Coll. i : 

 138; Polygonum imbricatum Nutt. ; Wats. Am. Nat. 7: 665 

 [Man. R. M. 319] ; not Raf. 



Margins of dried pools, at an altitude of 2000-2500 m. 

 Montana : Cedar Mts., July 16, 1897, Rydbcrg & Bessey, jj66. 

 Yellowstone Park : Mt. Evans, 1884, Txi'cedy, 25. 



* Polygonum unifolium Small. 



Annual, dwarf, glabrous. Stems erect, 1-3 cm. tall, simple, very 

 slender and wiry, naked or nearly so below ; leaves mostly solitary 

 at the middle of the stem ; blades narrowly linear, erect, 7-10 mm. 



