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Notes on some of the rarer Species of Polygonum. 
By Joun K. SMALL, 
(PLATE 224.) 
Some observations on the specimens of Polygonum, in the Her- 
baria of Prof. T. C. Porter, at Lafayette College, Mr. E. P. Bick- 
nell and the Academy of Natural Sciences at Philadelphia, as well 
as the Herbarium of Columbia College, lead to the recording of 
some notes on the rarer species. These I have thought best to 
arrange and print in the following form, in advance of the publi- 
cation of my monograph on the North American species of the 
genus. 
Potyconum Newserryvi Small, Bull. Torr. Club, 2: 170 (1894). 
The following Western collections should be referred to Fr: 
Newberryi: FE. Hall, No. 446, collected in 1871; T. J. Howell, 
Mt. Hood (6,000-8,000 ft.), collected in August, 1881; E. C. 
Smith, No. 747, Mt. Ranier, Washington, collected August, 1890. 
It may be interesting to note in this connection that glabrous 
forms of the above are related to P. Davisie of California, while 
the tomentose plants approach P. sericeum, of Siberia, in aspect 
PoLyGoNUM EMERSUM (Michx.) Britton, Trans. N. Y. Acad. Sci. 8: 
73 (1889). : 
Polygonum rigidulum Sheld. Bull. Geol. and Nat. Hist. Surv. 
_ Minn. 9: 14. 4 7 (1894). 
Mr. Sheldon has evidently been misled, in describing a form 
or state of P. emersum under the name P. rigidulum, by not being 
_ sufficiently acquainted with the former plant. I have examined 
between one and two hundred specimens of P. emersum from 
parts of North America, and cannot see that the characters 
assigned to P. rigidulum have any specific value. His distinguish- Se 
ing points are “ larger size, aquatic habitat, the geniculate, branch- i 
ing, tumid stems and the obcuneate, almost glabrous, obliquely oc 
attached leaves.” In the first place, P. emersum, like the other 
_ two members of the same group, P. amphibium and ote ‘ ‘ 
“wright, is very variable, although an exceedingly good species: 
_ and secondly, about one-half of the specimens I have exalt” 
