4 



cknell: Ferns and flowering plants of Nantucket 451 



tive of Polygonum ramosissimiim as a form of the typical western 

 species has pointed out a noteworthy difference between the two 

 plants in the color oi their flowers. In the western species the 

 calyx lobes are green and yellow; in the eastern plant tliey are 

 green and white, usually tinged with rose. The color differences 

 between the two plants are not however confined to the flowers. 

 The foliage of our coastwise plant is of a pale glaucescent green 

 which contrasts strikingly with the bright or deep yellowish-green 

 color characteristic of P. ramosissiiimni , the difference affording: a 

 close parallel to the color contrast between Polygonum avicnlare 

 L. and P. erectnni L. Nor are the differences between the two 



+ 



plants only those of color. The leaves of the eastern plant are as 

 a rule more uniformly acute and more tapering to base and apex, 

 longer-petioled, of thicker texture with revolute margins when dry 

 and much more strongly venose. In the western plant they are 

 commonly very smooth and flat and only obscurely venose. The 

 ochreae of the eastern plant are firmer, usually longer and more 

 stiffly laciniate and darker in color, the base often blackish. The 

 mature calyx of P. ramosissimnni is longer than that of P, atlan- 

 ticurn and of a somewhat different shape, 3-5-5 mm. long as 

 against 2.5-4 nim., ovoid-oblong rather than ovoid and more 

 gradually narrowed towards the base ; the calyx segments are 

 commonly broader, especially above, and more strongly venose 

 notwithstanding the less venose leaves. The achene of P. ramo- 

 sisslnium is larger and broader than that of P. atlanticiim and of 



w 



somewhat lighter and more reddish color. 



I have found no difficulty in properly assigning a large series 

 of specimens without reference to locality. Each species, however, 

 occurs well within the range of the other. Doctor Robinson has 

 recorded P. ramosissimiim from eastern Massachusetts and I have 

 ^^^n specimens of typical P. atlantiaim from North Dakota. 



P. ramosissimiim appears to be more closely related \o Polygonum 

 BellardiKW, of Europe than is P. atlantiaim and. certain specimens 

 of the European and of the more western American plant are 



scarcely distinguishable. 



In the study of these plants it has appeared that a beautifully 

 distinct unnamed species which has been included in P, ramosis- 

 sifmim occurs in Missouri — Atherton, Sept, 7, 1895, B. F. Busli, 



