STUDIES OF THALICTRACEAE — I. 55 



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differences in size, amplitude of panicles, forms of leaflets and 

 characteristics of them as to texture, venation and pubescence, 

 the whole genus outside of it is scarcely more diversified than 

 is the Leucocoma section in itself. Also its species range all 

 the way from subarctic Labrador to Georgia in the southern 

 United States, and from the Atlantic seaboard to the Rocky 

 Mountains. 



Thalictrum BissELUI. Slender, sparsely leafy, 2 feet 

 high, the solitary basal leaf petiolate, the several and remote 

 cauline sessile ; stems terete, scarcely angled or striate : leaf- 

 lets of low^est leaf of staminate plant glabrous on both faces, 

 glaucous-green above, very glaucous beneath, suborbicular, 7 

 or 8 lines wnde, subtruncate or subcordate at base, slightly 

 and not very unequally 3-lobed at apex, with middle lobe 

 about twice as broad as long, truncate, but, by tw^o slight 

 indentations broadly 3-crenate, the terminals and laterals little 

 different save as to size ; upper leaves of same staminate plant 

 sparsely and minutely pubescent beneath : leaflets of pistil- 

 late plant rather longer than broad, more deeply 3-lobed, the 

 middle lobe rounded at apex and perfectly entire ; sepals of 

 staminate plant obovate, obtuse, of pistillate equally obtuse 

 and more rounded, almost orbicular: filaments short, clavel- 

 late almost from the base, much narrower at their widest than 

 the short oblong-oval anthers : immature achenes small , 

 slenderly fusiform and stipitate. 



Type specimens collected in 1897, in the middle of July, at 

 Southington, Connecticut, by C. H. Bissell, whose label 

 records it as common there in wet meadows. The specimens 

 are wnth me as a loan from the herbarium of the Agricultural 

 College of New Mexico. 



For a member of this white-stamened group this is a small 

 one, the plants not larger than some of the largest of T. 

 dioicum, and is quite as sparingly leafy as that is in its larger 

 grow^ths. The sheet of specimens is a remarkably complete 

 one, bearing a complete staminate and a complete pistillate 

 plant, each in flower, with also an inflorescence of the pistil- 



