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76 



In the shape and basal termhiation of the fruit. The form of the 

 uiflorescence may be used subordinately, after this the compara- 

 tive number of the stigmas, and finally the terrestrial or floating 

 habit, and the size of the fruit and styles. 



Embodying these principles I am led to adopt the following 

 classification, and to give afterwards a more detailed description 

 of the American forms. ' 



A.— FRUIT SESSILE AND COMPARATIVELY BROAD. 



I. — Inflorescence simple. 



S, subglobosurn. 



II. — Inflorescence branching. 



1. Stigmas commonly 2, occasionally I. 



S. eurycarptim, Engelm. 



2. Stigmas commonly i, occasionally 2. 



S, ramosum, Curtis, S, Greenei, S. negledttm^ Eecby. 



B^FRUIT STIPITATE AND COMPARATIVELY NARROW 

 1. — Stems erect or floating, inflorescence branching. 



The heads are numerous on the widely branching inflorescence 

 the staminate from six to fourteen on a branch, the pistillate 



Paper read before the Cal. Acad. Sci., Feb. 4, 1884, p. 4. 



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S.androdadum, Eglm.; ^zx. fluctnans. Possibly the true .S*. natans of 

 Linnceus and Fries belongs here. 



II. — Inflorescence simple. 



1. Erect or floating, styles and fruit conspicuous, leaves triangular except when | 

 floating. 



5. simplex^ Huds., var. angitstifolium^ { Michx.), Engelm. S,JluilanS,^T^'^^^i 

 if really a distinct species, would belong here, but perhaps it is nothing 

 more than a form of S, simplex, 



2. Usually floating, stems very slender, fruit and styles small, leaves flat. 



S. ni'iHimiun^ Fries. 6', hyperboreum^ Lsest. 



S. oligocarpon^ Angstr., as figured and described in Fl. Dan. Supp-j "T^^^- 



172, might belong to S. minimum or S. hyperhoremn. It seems to be 



very rare, and its rank not fully established. 

 S, Greend and S. negleihim are evidently transition forms, as the more 



sloping summit and narrower outline of their fruit show. (See Figs. 3 



and 4 in the plate.) 



The North American species are as follows : » 



I. 5. enrycarpimi^ Engelm. (Gray. Man., Ed. 5, p. 481.) 



The largest member of the family, 9dm.-i5clm. high. Prof- 

 E. L. Greene sends a specimen which he has named S. Call- 

 fornicum^'^ but which T am unable to separate from 5'. etirycarpufftt * 

 which measures 26 dm. in heie^ht and the leaves over 26 dm. long- 



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