32 BOTANICAL GAZETTE. 



Mass., by Rev. H. G. Jesup, in 1874, and by him sent to Dr. Rob- 

 bins, who thereupon substituted the name here given. 



Aug. , Sept. Slow moving streams and still water in various parts 

 of New England. 



P. NiAGARENSis, Tuckerman. — Intermediate forms between this 

 and P. pauciflorus, Pursh, have been found within a few years past, 

 rendering it doubtful whether its old rank m Ed. 4, Gray's Man. , as 

 a variety of paucifloriis, should not be restored. The writer collected 

 specimens in sluggish creeks and pools near the mouth of the river 

 Niagara which have the foliage of pauciflorus and the fruit of Niaga- 

 rensis. Rev. E. J. Hill has found an equally doubtful form in great 

 abundance at South Chicago, 111., and the same comes from Canada. 

 A larger number of specimens, and a closer examination may make 

 it necessary to unite the two under the older name. 



P. PECTiNATUS, L. — Particular attention is called to this species, as 

 quite a number of abnormal forms have been discovered since the is- 

 sue of Dr. Robbins' monograph, especially in the regions west of the 

 Mississippi, and some of these may prove to be distinct species. It 

 is hoped that additional specimens and notes from botanists in the 

 field will render a good definition possible. 



P. ZOSTERACEUS, Fries. -Similar in general appearance to P. pedina- 

 tus, but stouter; leaves flat, 1-3 inches long by 1-2)^ lines broad, 3- 

 5 nerved, with many cross veinlets, amplexicaul, obtuse or acute ; 

 stipules adnate to the base of the leaves, obtuse, shorter and narrower 

 than the striate, scarious-margined sheaths; peduncles slender, 1-4 

 inches long ; flowers in verticils more or less distant ; fruit agreeing 

 with that of /<'^///?f7///j in size and shape, but rather more flattened, 

 the style long and recurved, and the apex of the embryo pointing trans- 

 versely inwards 



California. P. peciiiiatus, var.? latlfoliiis, Robbins in Bot. King's, 

 Ex. 338. As figured by Reichenbach, this species has drooping pedun- 

 cles 8 inches in length, with verticils of fruit i^ inches distant, but 

 the writer has authentic European specimens which agree with our 

 form in every particular. 



P. MARiNUS, L. — Low (3-6 inches) and leafy, with many dichoto- 

 mous branches ; leaves all submerged, thick, setaceous, i nerved, 

 with a few transverse veinlets, obtuse or acute, 2-4 inches long ; 

 stipules adnate to the base of the leaves, shorter than the sheaths 

 which have narrow, scarious margins, sometimes white ; peduncles 2- 

 3 inches in length ; spikes interrupted or in approximate verticils , 

 fruit subglobose obovate, i-r^ lines long and ^ to i line wide, ob- 

 tuse on the margins, crowned with a broad sessile stigma, the em- 

 bryo circle incomplete and the apex pointing to the base, usually cor- 

 rugated when dry. 



The European form differs only in having peduncles 3-6 inches in 

 length. 



Aug. {P. Jilifonnis, Nolte). By some good botanists reckoned as a 

 variety of P. pccHnatus, but the fruit is clearly distinct. 



