194 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



KEY TO THE SPECIES. 



Inflorescence aggregated at the ends of the branches; plants 



small, less than 10 cm. high 1. P. watsoni. 



Inflorescence of small scattered axillary clusters; stems 20 

 cm. long or more. 

 Stems prostrate (except where the plants are much crowded, 

 there weakly ascending) . 

 Leaves thin, not prominently veined, bright green; 



ocrese not conspicuous 2. P. aviculare. 



Leaves thick, with rather prominent veins, pale or 



glaucous; ocrese conspicuous 3. P. buxiformc. 



Stems erect. 



Achenes not deflexed. 



Upper leaves little reduced; plants bright green 4. P. erectum. 



Upper leaves much reduced, bractlike; plants 

 bright or yellowish green. 

 Upper leaves or bracts not subulate, mostly 



elliptic or lanceolate; achenes dull.... 5. P. ramosissiviwn-. 

 Upper leaves reduced to subulate bracts; 



achenes black and shining 6. P. sawatchense. 



Achenes deflexed. 



Upper bracts much reduced, subulate; lower 



leaves mostly narrowly lanceolate or linear. . 7. P. douglasii. 

 Upper bracts broader, oblong to lanceolate; lower 



leaves broader, elliptic to oblong-lanceolate.. 8. P. montanum. 



1. Polygonum watsoni Small, Mem. Bot. Columb. Coll. 1: 138. pi. 56. 1895. 

 Type locality: "Washington to Montana; south to California and Colorado." 

 Range: As under type locality. 



New Mexico: Tunitcha Mountains; Chama. Wet ground, in the Transition Zone. 



2. Polygonum aviculare L. Sp. PI. 362. 1753. 



Type locality: "Habitat in Europae cultis ruderatis." 



Range: Common throughout North America except in the extreme north; also 

 in the Old World. 



New Mexico: Santa Fe and Las Vegas mountains; Dulce; White Mountains; 

 Roswell. Upper Sonoran and Transition zones. 



A common dooryard weed at middle levels in the mountains. The plant is rather 

 variable in general aspect, being influenced by the conditions under which the 

 individuals have grown. 



3. Polygonum buxiforme Small, Bull. Torrey Club 33: 56. 1906. 

 Polygonum littorale Link, err. det. Small, Mem. Bot. Columb. Coll. 1: 102. 1895. 

 Type locality: Not stated. 



Range: Throughout North America except in the extreme north. 



New Mexico: Farmington; Tunitcha Mountains; Las Vegas; Bernalillo; Maxwell 

 City; Santa Fe; Kingston; Mangas Springs; Mesilla Valley; Sacramento and White 

 mountains. Damp ground, Lower Sonoran to Transition Zone. 



This species seems too near the preceding, and it may be that Doctor Robinson's 

 treatment of it as a subspecies is correct. Usually this plant is less green, a little 

 stouter, and the ocreae are more conspicuous, but the differences are more of degree 

 than kind. 



4. Polygonum erectum L. Sp. PI. 363. 1753. 

 Type locality: "Habitat in Philadelphia." 



Range: Throughout the United States as far west as the Rockies. 

 New Mexico: Chama; Sierra Grande. Waste ground. 



