214 Karl M. Wiegand and Arthur J. Eames 



14. R. bulbosus L. Bulbous Buttercup. 



Sandy fields and banks, in acid or neutral soils; scarce. May 15-June 15. 



Sporadic plants have been found near Six Mile Creek (Miss A. G. Mekeel), near 

 gravel beds at mouth of Fall Creek, and at Venice Center (A. H. Wright). The 

 species is more firmly established in Paine Creek glen (D. !), at Aurora near the rail- 

 road (£>.), near Scipioville (abundant), on Howland Island, and along the road 

 between West Junius station and the marl ponds. 



N. E. to N. Y., southw. to N. C, Tenn., and La. So abundant on the Coastal 

 Plain and in the acid soils of N. E. as to paint the fields yellow when in flower. 

 Naturalized from Eu. 



15. R. acris L. Tall Field Buttercup. 



Fields and roadsides, in various soils, chiefly heavy and moist; very common. May- 

 Oct., mostly June 15-July 15. 



Newf. to B. C, southw. to Va. and Mo., including the Atlantic Coastal Plain. 

 Naturalized from Eu. 



The var. Steveni (Andrz.) Lange, with the leaf divisions broad, cuneate-obovate, 

 and slightly incised, is occasional. This seems to be in some cases merely a juvenile 

 form of the normal plant; in other cases it may represent leaf variation in individual 

 plants. 



Along the coast there are two periods when the fields are yellow with butter- 

 cups : an early one due to the flowering of R. bulbosus, and a later period when R. 

 acris is in flower. 



9. Thalictrum (Tourn.) L. 



a. Foliage not glandular and not heavy-scented ; leaflets thin, slightly veiny, the 

 margins nearly flat. 

 b. Filaments capillary, strongly drooping; flowers greenish yellow or greenish 

 purple, dioecious, vernal; petioles of the cauline leaves well developed; plant 

 3-7 dm. high. 1. T. dioicum 



b. Filaments clavate, ascending or spreading until after anthesis ; flowers white, 

 rarely purplish, less completely dioecious, aestival ; petioles of the cauline 

 leaves very short; plant 5-26 dm. high. 

 c. Achenes glabrous. 2. T. polygamum 



c. Achenes pubescent. 2a. T. polygamum, 



var. hcbecarpum 

 a. Foliage conspicuously glandular, heavy-scented ; leaflets firm, veiny, with revolute 

 margins ; filaments capillary or slightly thickened ; petioles and habit as in the 

 preceding species. 3. T. revolutum 



1. T. dioicum L. Early Meadow Rue. 



Dry rocky and gravelly soils, and along ravine banks, in neutral or slightly alkaline 

 soils ; frequent, and generally distributed. Apr. 20-May 15. 



Mostly absent from the chestnut-vaccinium woods, as it is not a plant of acid sands. 



Cent. Me. to Sask., southw. to Ala. and Mo. ; rare on the Coastal Plain and not 

 characteristic of that region. 



2. T. polygamum Muhl. Meadow Rue. 



Swamps and meadows, in various soils ; common. July. 



Newf. to Ont. and Ohio, southw. to Fla., including the Coastal Plain. 



House would adopt the name T. canadense Mill, for this plant, but both T. cana- 

 dcnse Mill, and T. Cornuti L. were founded on Cornut's plate, with regard to which 

 see Gray's Synopt. Flora, vol. 1, pt. i, p. 18, 1895. 



