Wjegand : Some Species of Bidens 415 



This species is one of the most variable of the whole group 

 almost all portions of the plant being subject to change. In New 

 England the leaves are shorter petioled, while in the West the 

 petioles are often very long (4 cm.). Some specimens from the 

 Eastern and Middle States have much narrower, nearly sessile 

 leaves. Specimens from Ithaca, N. Y., and Ohio (Selby) as welt 

 as one in the National Herbarium collected by Dr. Vasey near 

 Washington have upwardly barbed awns but other characters the 

 same as in the type. At Ithaca these upwardly barbed plants 

 grow over a considerable area almost to the exclusion of the nor- 

 mal form ; but many transitional specimens were found in which 

 the awns bore barbs extending in either direction. In addition to 

 these variations one often finds in sphagnous bogs and especially 

 on decaying logs along the borders of lakes, pools and slow^-flow- 

 ing streams a very small form (5-20 cm.) bearing one or two few- 

 flowered oblong heads, and small, spatulate-oblong, petioled, 

 nearly entire leaves. However, when the place of growth becomes, 

 more congenial it seems to pass directly into the normal form. 



A very interesting form is the var. pinnata Wats! from Minne- 

 sota. It seems to have a very limited range, being confined to 

 two or three localities in the vicinity of St. Paul. The pinnate 

 finely divided leaves and smoothish achenes make it a very con- 

 spicuous plant, and almost specifically distinct. The limited distri- 

 bution at first suggested its being a hybrid ; but no other species, 

 is known that could give such a combination of characters with B.- 



I 



connata. It should be looked for in other districts of the West. 



The question as to whether Muhlenberg's type was really this 

 species or B. comosa is a somewhat perplexing one. It seems,, 

 however, to benow quite definitely settled that the present interpre- 

 tation is correct, both from a study of the original description, and 

 from specimens which Prof. Aschcrson has compared with the 

 Muhlenberg material at Berlin, and which the writer has had an 

 opportunity to examine through the kindness of Dr. Robinson. 



B. connata^ has in recent years found its way into pAirope. 



* The literature upon the occurrence oi B. connata in Europe is as follows : 

 Warnstorf, Verhand. d. Bot. Verein. d. Trov. I5randenb. 21 : 157. 1S79. Oes- 

 terr. Eot. Zeitschr. 10 : 392. 1895 ; 12 : 475. 1895. Bot. Gaz. 25 : 58. 1898. 

 Ascherson, Verhand. d. Bot. Verein. d. Brov. Brandenb. 37 : L. 1895 ; 38: 



Liii. 1896. 39: xc. 1897. r 



