510 MINNESOTA BOTANICAL STUDIES. 



KEY TO .SPECIES OF THALICTRUM. 



A. Natives of United States or introduced. 

 B. Flowers perfect. 



C. Filaments widened above ; anthers ovate, obtuse. 



D. Akenes sessile, in a head, ovate oblong petaloideum. 



DD. Akenes stalked, widely spreading, straight along dorsal 

 margin. 



E. Styles very short; stigma almost sessile ,clavatum. 



EE. Styles as long as width of akene sparcijlorum. 



CC. Filaments filiform ; anthers linear, acute, or mucronate. 

 D. Stigma hastate or spurred ; flower-stem abruptly recurved 



near the fruit alpinum. 



DD. Stigma not spurred nor hastate. 



E. Fruits sulcate; stigma dilated on one side of the short 



style minus. 



EE. Fruits longitudinally veined ; stigma terminal, minute, 



not dilated, style short glazicum, 



BB. Flowers polygamo-direcious. 



C. Anthers linear, mucronate; filaments thread-like. 



purpurascens. 

 CC. Anthers ovate, obtuse ; filaments broadened above. 



polygamum. 

 BBB. Flowers direcious, with rare exceptions. 



C. Filaments widened above ; anthers ovate, rather obtuse. 



aquilegifolium . 



CC. Filaments thread-like; anthers linear, acute or mucronate. 

 D. Mature fruits rather firm or thick-walled, not greatly flat- 

 tened, filled by the seed; leaves glabrous. 

 E. Blades of leaflets very thin. 



F. Roots tuberous ; stem reclining debile. 



FF. Roots coarsely fibrous ; stem erect dioicum. 



. EE. Blades of leaflets firm, veiny below. 



F. Styles clubbed Caulophyttoides. 



FF. Styles not clubbed. 



G. Akenes well stalked coriaceum. 



GG. Akenes nearly sessile -venulosum. 



DD. Mature fruits less firm, thin-walled, 2-edged, either flat- 

 tened or turgid. 



E. Leaflets very thin occidentale. 



EE. Leaflets firm. 



F. Pistils 5-11 (rarely 13) Fendleri. 



FF. Pistils 7-20 polycarpum. 



AA. Natives of Mexico, not introduced into United States. 

 B. Leaflets peltate or subpeltate. 



