WiK(;Axr3: Some Species of Bidens 407 



and leaflets very broad. In the vicinity of sphagnous bogs it often 

 becomes more bushy, with smaller leaves and more acuminate 

 leaflets, in which condition it resembles B, discoidca very closel}*. 

 The specimens with upwardly barbed awns collected by various 

 botanists and thought to be hybrids between this species and B. 

 discoidca or B. bidcntoidcs can scarcely be considered as such since 

 they do not show the necessary intermediate condition of other 

 characters. In fact, with the exception of the barbs, all the char- 



r 



acters are identical with those of this species. It seems better for 

 the present to consider them as accidental forms of />. uielanocarpa. 



+ 



B. inclanocarpa cannot be distinguished from the other species 

 of North America by any one character. From B. frondosa it 

 differs by its fewer involucral bracts, narrower upwardly barbed 

 achenes and orange flowers ; from B. connata by its 2-awned 

 achenes and pinnate leaves; from B, discoidca by the larger, less 

 acuminate leaflets, and larger more tuberculate and longer-awned 

 achenes and more numerous involucral bracts. It is very closely 

 related to B. tripartita of the Old World, some of the broader 

 leaved forms of which differ only in having blunter teeth and 

 downwardly barbed achenes with yellow corollas. It seems to 

 form a transition between B. tripartita and B. connata on the one 

 hand and between B. discoidca and B. connata on the other. 



The var. pallida although widely distributed, judging from the 

 specimens representing it in the larger herbaria, seems not to be 

 very common. In the vicinity of Ithaca, N. Y., however, it is 

 abundant along the shores of Cayuga Lake, where its habit makes 

 it quite conspicuous. In many respects the reduction of the leaves 

 and lengthening of the peduncles suggests a condition similar to 

 that w^hich in B. connata and B, conwsa was determined to be a 



^^ b I 



'''second growth,'* but here the plants seem to be perfectly normal 

 and healthy. Moreover they differ in some important structural 

 characters regarding the head and achenes, and in the long 

 branches overtopping the terminal head. Considering the charac- 

 ter of the heads and achenes alone, it might almost be taken for a 



hybrid with B. conwsa, but the leaves and general habit are not at 

 all intermediate. It seems best at present to consider these forms 

 as forming a distinct variety. The flowering period of B. mclano- 

 carpa is from Aug. 15th to Sept 25th. 



