110 POLYGON ACEAE. 



Plants with the upper leaves more scattered and reduced, mostly erect perennials. 

 Upper bracts not subulate ; achencs dull. 



Lobes of the perianth with yellowish margins; perianth 3-4 mm. long; 

 achenes about 3 mm., nearly smooth. 4. F. ramosissimum. 



Lobes of the perianth with whitish or pinkish margins ; perianth 2-3 mm. 

 long; achenes 2-2.5 mm. long, distinctly granulate or striate. 



5. P. rubcscens. 

 Upper bracts subulate ; achenes smooth and shiny. 6. P. sawatchetxse. 



Inflorescence aggregated at the ends of the branches ; bracts leaf-like and usu- 

 ally broader than the narrowly linear leaves ; plants dwarf annuals. 

 None of the perianth-lobes keeled. 



Leaves several, gradually merging into the bracts ; achenes blunt-angled and 



strongly striate. 7- J^- IVdsonii. 



Leaf usually solitary and much longer than the bracts ; achenes sharp-angled 

 and obscurely striate. 8. P. unifolium. 



Some of the perianth-lobes keeled near the apex. 9. P. Kelloggii. 



Fruit reflexed. 



Upper bracts much reduced and subulate. 



Perianth 1.5-2 mm. long; leaves narrowly linear; achenes exerted. 



10. P. Engelmannii. 

 Perianth 4-5 mm. long ; lower leaves oblanceolate to linear-oblanceolate ; 

 achenes included. 11. P. Douglasii. 



Upper bracts foliaceous, relatively broad, lanceolate or oblong. 



Achenes included. 12. P. montanum. 



Achenes exserted. i3- P- commixtum. 



1. Polygonum erectum L. In waste places from Me. and Alb. to Ga. and 

 Ark. and Kans. Also reported from Colorado, but no exact locality given. 



2. Polygonum buxiforme Small. {P. litorale Small, in part) In sandy 

 and alkaline soil from Ont. and Wash, to Va., Tex. and Nev. — Alt. 4000-10,000 

 ft. — Georgetown; Silver Plume; along Platte River, Denver; Montrose; Fort 

 Collins; Colorado Springs. 



3. Polygonum aviculare L. In waste grounds from Newf. and Sask. to 

 Va. and Calif.; introduced from Europe. — Alt. 4000-8000 ft. — Fort Collins; 

 Gunnison. 



4. Polygonum ramosissimum Michx. In river valleys and low ground from 

 Minn, and Wash, to Ills., N. M. and Nev. — Alt. 4000-10,000 ft.— Cheyenne 

 Mountain ; Fort Collins ; Upper La Plata Cafion. 



5. Polygonum rubescens Small. In sandy soil from Ida. to Colo, and Utah. 

 — Alt. 4500-8000 ft. — Parlin, Gunnison Co. ; Larimer Co. 



6. Polygonum sawatchense Small. On hillsides from S. D. and Wash, to 

 Colo., Ariz, and Calif. — Alt. 4000-9000 ft. — Saguache Range; Box Caiion, 

 west of Ouray ; Calhan ; Veta Pass ; Estes Park. 



7. Polygonum Watsonii Small. {Polygonum imbricatum S. Wats.) In wet 

 places from Mont, and Wash, to Colo, and Calif. — Alt. 6000-10,000 ft. — 

 South Park; Leroux Park; Upper West Mancos Canon; Chambers' Lake. 



8. Polygonum unifolium Small. In wet places from Mont, to Colo. — Ten- 

 nessee Pass. 



9. Polygonum Kelloggii Greene. In wet soil from Wash, and Mont, to 

 Calif. — Alt. 6000-10,000 ft. — Steamboat Springs; Bard Creek Valley, near 

 Empire. 



10. Polygonum Engelmannii Greene. (P. tenuc microspermum Engelm.) 

 On hillsides and mountains from Mont, and B. C. to Colo. — Alt. 5000-10,000 



