310 



New or Noteworthy North American Phanerogams.— III. 



By N. L. Brixton. 



Ranunculus Porteri, n. sp. § Batrachium. Submersed, 

 apparently several feet long, freely branching. Leaves petioled, 

 the petioles Y^ to i' long, and dilated at the base, the 

 blade about i ^' in diameter repeatedly ternately divided into 

 linear or capillary segments ; the upper shorter and broader; 

 flowers white, 3" to 4" broad, peduncled ; achenes 6 to 12 in a 

 head, obliquely oval, compressed, somewhat pubescent, margin- 

 less, very nearly \" long, beakless or with a mere apiculation, 

 irregularly rugose transversely ; receptacle pubescent. 



I noticed this plant in Dr. Porter's Herbarium a year or so 

 ago. The accompanying label has only ** Henry's Fork, No. 

 1062 ; Raiiunctilus, entirely immersed." It was collected on the 

 Hayden Survey of the territories, but I cannot place the exact 

 locality. 



The species differs from any form of R. aqtiatilis with which 

 I am acquainted, in its much broader and fewer leaf-segments 

 and larger achenia. I sent it to Mr. Baker at Kew, who thinks it 

 not related to any European form of that plant, remarking that 

 " no European form ever shows so much transition between float- 



