1902] NOTES ON CERTAIN 



115 



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regards our eastern Antennarias this remains to be done for 

 most of them. 



The plantain-leaved species are very polymorphous and 

 almost indistinguishable. It would not be at all difficult in any 

 large collection to spread out a series of specimens exhibiting a 

 gradation of A, neglecta through A. petaloidea and A. ambigens 

 into A, Parli?in, In spite of the frequent intergradations we do 

 recognize as tolerably well marked some categories of forms to 

 which it seems proper as well as desirable to assign binomial 

 names. Though authors will to some extent differ in judgment 

 as to the validity of certain species, it is gratifying to note 

 that different investigators in this group in several instances have 

 reached the same conclusions. 



In the segregates of A. plantaginifolia, A, dioica, and A. alpina 

 of earlier American authors, the general habit and stature of the 

 plant, the outline and size of the leaves, the character and per- 

 manency of the pubescence, and the height of the involucres are 

 of most value for specific diagnoses. The outline of the bracts 

 of the pistillate involucres, especially as regards the bluntness or 

 acuteness of their tips, are of minor importance in distinguishing 

 species. In most of the eastern as well as of the western Anten- 

 nanas I have found that the tips of the involucral bracts (pistil- 

 late) vary from obtuse to acute or acuminate. The outh"ne of 

 the bracts has quite generally been given in recent descriptions, 

 and the bluntness or acuteness of their tips has in many instances 

 been taken as one of the distinctive characters of certain species 

 and sub-species. The amount of thickening or dilation of the 

 pappus bristles of the staminate flowers is also found to be sub- 

 ject to considerable variation in the same species. 



It is a well established fact that parthenogenesis occurs in the 

 real Antennaria alpina. While there is at'present no evidence to 

 show that any North American species are propagated partheno- 

 genetically, it perhaps would not be at all surprising to find that 

 »t does take place in some of them. We at least know that 

 good seeds may be produced. Mr. Theo Holm, of Brookland, 

 • C., assures me that he has observed in that vicinity an abun- 



