2gi 



BOTANICAL GAZETTE. 







its habitat is described by Mr. Hill in the number for Sept. 1881. 



Excellent specimens, obtained in Aug. 1880, by Mr. Hill, at Manistee, 



Michigan, have been 

 sent to England for 

 comparison with the 

 forms at Kew and 

 London, and have 

 also been compared 

 with all our known 

 American forms, 

 with the result above 

 stated. It is now 

 named for Mr. Hill 

 who has done so 

 much for its elucida- 

 tion. 



Stem about i foot 

 in height, slender, 

 widely branching. 

 Leaves all submerg - 

 ed, linear, acute, i- 

 2)4 inches long and 











y2--^K 



1. p. zosterifolius, Schum. 



2. P. acutifolius, Link. 



3. P. Hillii. 



lines wide, 

 3- nerved, the lateral 

 nerves delicate and 

 nearer the margins 

 than the midrib, the 

 midrib often com- 

 pound below, sti 

 pules free, whitish, striate, obtuse, 3-5 lines in length. Pedun- 

 cles short, spreading or somewhat recurved, more or less clavate ; 

 spikes capitate, 3-6 fruited. Fruit obliquely obovate, about i^ lines 

 long by lyi lines broad, tricarinate on the back, the middle keel more 

 or less undulate, compressed on the sides, the front slighdy arched, 

 obtuse at base; style nearly facial, short, recurved; embryo apex 

 pointing transversely inwards. 



New York and Michigan, August. 



In general appearance similar to P. pauciflorus, but allied by its 

 fruit to the zosterifolius group, and especially to P. acutifolius, Link., 

 which it greatly resembles in the spikes and fruit.* — Thomas Mo- 



RONG. 



*The above tigures, drawn from specimens in my possession, wil I 

 serve to show the similarity between tlie spikes and fruil of the three species 

 above mentioned. In all these cases tlie dorsal keel is undulate on the maririn : 

 it is sometimes distinctly toothed or entire. It should he siid, also, that 

 while the common form of the nutlets of F. zoHtevifoUiiK and P. (iruUfoUm is 

 sliown, the European specimens often have a sharp projecting angle on the 

 face, about one-third of the distance Irom the base, a peculiarity which I have 

 not observed in tlie American P . zosterifolius or P. Hillii. 



a. nutlet much magnified ; h. embryo of the same ; c. natural size ; d. fruit spike. 



