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............ sparciflorum. 
CC. Filaments filiform; anthers linear, acute, or mucronate. 
D. Stigma hastate or spurred; flower-stem abruptly recurved 
WGN MCINE Ss ose «tee nsec ee aisaelos saber ee aeeeae alpinum. 
DD. Stigma not spurred nor hastate. 
E. Fruits sulcate; stigma dilated on one side of the short 
BEVLE fen ieaie heme te sh ete ean he wtee Ces weenie hoe anda eee Minus. 
EE. Fruits longitudinally veined; stigma terminal, minute, 
not dilated styleschomi): lessee. Ha estes cee glaucum. 
BB. Flowers polygamo-dicecious. 
C. Anthers linear, mucronate; filaments thread-like. 
purpurascens. 
CC. Anthers ovate, obtuse; filaments broadened above. 
polygamum. 
BBB. Flowers diccious, with rare exceptions. 
C. Filaments widened above; anthers ovate, rather obtuse. 
agutlegtfolium. 
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. 
EF . “Reptstuberous> stem reclining J)... J. ccs saeco debile. 
FF. Roots coarsely fibrous; stem erect............. dioicum. 
EE. Blades of leaflets firm, veiny below. 
By ky LCS (CHU DEG, cara sp concmes ec -habeseae Caulophylloides. 
FF. Styles not clubbed. 
G. Akenes well, stalked 22. 032.20 .c-steyeeeesees corzaceum. 
GG. Akenes*meanly Sessilesa. ssc: con acusn sees venulosum. 
DD. Mature fruits less firm, thin-walled, 2-edged, either flat- 
tened or turgid. 
iB,  eLsealetstveny ar hilaces ieee cerca sae seria eat serorons occidentale. 
EE. Leaflets firm. 
E’.. Pistils orn Wrareliy ns) acasste.adess codecs eee fendlert. 
UE. WPistilss 720. cere sdeee. BARU eden ols sak ctael polycarpum. 
AA. Natives of Mexico, not introduced into United States. 
B. Leaflets peltate or subpeltate. 
