IRbofcora 



JOURNAL OF 



THE NEW ENGLAND BOTANICAL CLUB 

 Vol. 23. March, 1921. No. 267. 



THE GENUS ECHINOCHLOA IN NORTH AMERICA. 



K. M. WlEGAND. 



In the seventeenth volume of this journal (Rhodora xvii. 105. 

 1915) Fernald showed that in eastern North America we have, in 

 addition to Eckinochloa crusgalli L. and the maritime E. Walteri 

 (Pursh) Nash, another species, E. muricata (Michx.) Fernald. In 

 the field the writer has noted other forms of Eckinochloa which were 

 not easily placed in any of the described categories. For this reason 

 an investigation of the genus was attempted, the results of which 

 are presented in the following pages. The study soon led into the 

 warmer portions of America where the genus is well represented, 

 and it was decided to include in the treatment all of the region north 

 of Panama. Our knowledge of some of the forms, especially from 

 the tropics, is as yet fragmentary, and more material will doubtless 

 modify the ranges, and perhaps in some cases even the limits of 

 species. This paper was nearly ready for the press when the recent 

 revision of the genus Eckinochloa by Hitchcock (Contr. U. S. Nat. 

 Herb. xxii. pt. 3, 133-153. 1920) was received. The two treatments 

 were found to differ so widely that the publication of the paper still 

 seemed wise. 



The species of Eckinochloa do not fall into well-marked groups 

 and almost every character that may be selected to define a group 

 presents one or more exceptions, so that the construction of a key 

 or synopsis has been extremely difficult; yet to one engaged in their 

 study the ultimate species and forms seem well marked. Besides 

 the size and form of spikelets and size and nature of the spinules, 

 the length of the anther has been found of service in indicating rela- 

 tionship and in helping to establish boundaries between species. 



