BiCKNELL : 



Nantucket 



* Persicaria tomentosa (Schrank) comb. nov. 



Polygomun tomentoswn Schrank, Baier. Fl, i : 669. 1789. 



A few good-sized plants back of the sandy shore oi Miacomet 

 Pond, Sept. 21, 1899, in full flower. Plants erect, the larger 

 about 6 dm. high, some of the leaves invested on the lower sur- 

 face with bluish-white tomentum, others quite glabrous ; many 

 with a dark medial blotch on the upper surface. 



Persicaria Persicaria (L.) Small. 



Common, especially in and near the town. In full flower 

 through August and September. 



Persicaria hydropiperoides (Michx.) Small. 



Common in ponds and water holes, flowering through August 

 and September. 



Persicaria opelousana (Ridd.) Small. 



Frequent in wet places in meadows and about ponds, flowering 

 in August and September : Tom Never's Swamp ; near Acquid- 

 ness Point ; Reed Pond and other ponds west and southwest of 

 the town. 



The range of this species is not understood to extend north of 

 Louisiana and Missouri, yet it is common enough in our eastern 

 flora and has doubtless been passed over as a pale-flowered form 

 of P, hydropiperoides^ to which it is nearly allied. Indeed the two 

 species have recently been united (Gray's New Manual, seventh 

 edition), but I have found myself unable to accept this ruling. 

 Some years ago I used to find both plants in the neighborhood of 

 Van Cortlandt Park, New York City, and carefully studied them 

 out as distinct without then suspecting that one was a southern 

 species already described. The eastern pale-flowered plant does, 

 indeed, differ in some respects from typical P, opelotisana^ but 

 apparently not by any character stable enough to justify their 

 separation. 



The most obvious differences between our eastern plant here 

 referred to P. opeloiisana and P, hydropiperoides are s^^n in the 

 flowers. In the latter species these are ovoid-oblong, 2.5-4 mm. 

 long at maturity, purplish-pink to clear pink and white, the seg- 

 ments petaliferous and completely concealing the achene ; in P 

 opelousana the flowers are greenish-white, obovoid, 2-I mm. long, 



