1916] St. John, — Potamogeton, Section Coleophylli 129 



Hill and by himself, and from one other station in the same state. 

 His illustration was drawn from English specimens supplied him by 

 Mr. Fryer. Following Morong, this species has been kept as a North 

 American plant in Gray's Manual, in Britton and Brown's Illustrated 

 Flora, and in Taylor's treatment in the North American Flora. The 

 leaf characters of P. interruptus as stated by its defenders are admit- 

 tedly inconstant. 1 The fruit character, which is the main claim of 

 P. interruptus to specific rank, seems to be just as inconstant, at least 

 in the American plants, as the foliage character proves to be in the 

 European ones. In a single spike, such as that on the sheet collected 

 by L. L. Dame at Nantucket, Massachusetts, now in the Herbarium 

 of the New England Botanical Club, can be seen fruits which have 

 prominent dorsal keels as does P. interruptus, and also fruits with 

 evenly rounded backs as in P. pectinatus {stricto sensu). 



A quotation from a letter written by Mr. Arthur Bennett to Prof. 

 M. L. Fernald throws an interesting light on the status of P. interrup- 

 tus Kit. (P. flabellaitis Bab.) in North America. "Having occasion 

 to look through all my interruptus specimens, I was surprised to find 

 attached to the sheet of Manistee specimens sent me, a letter from Prof. 

 Babington dated 9, 2, 1882 in which he says 'Certainly I do not think 

 that the Revd. Morong's plant is Pot. flabellatus. The habit of the 

 flowering part is totally different from any specimens of my plant 

 that I have seen.'" Bennett continues, "I cannot now understand 

 why he [Morong] doubted Babington's decided opinion that it was 

 not his J label 'hit us." Whether or not the European specimens of P. 

 pectinatus will allow a division into P. pectinatus in its limited sense 

 and P. interruptus (which is very doubtful), it seems to be clear that 

 Morong was not justified in including P. interruptus as an American 

 species. Likewise the more recently collected specimens and pub- 

 lished notes seen by the author have not convinced him that any 

 American plants can properly be treated as P. interruptus Bab. 



P. columbianus Suksdorf 2 is worthy of mention in this connection, 

 since it is not included in the Pfianzenreich or the Index Kewensis. 

 Neither the duplicate-type material nor the description show any 

 distinctive characters to separate it from P. pectinatus. 



W. R. Dudley discusses 3 two plants from Cayuga Lake, New York, 



1 Fryer, Journ. Hot. xxvii. 59 (1889). 



'- Suksdorf. Deutsche Hot. Monatschr xix. 02 (1001). 



I Dudley, Cayuga Flora 107 (1880). 



