COXTRTBUTIONS FROM THE GRAY HERBARIUM OF HARVARD 



UNIVERSITY. 



New Series. - No. XXXIII. 



REVISION OF THE GENUS SPILANTHES. 

 By Albebt Haxford Moobe. 



Presented by B. L. Robinson, October 10, 190G. Received November 10, 1906. 



Introduction. 



When this revision was undertaken, the genus Spilanthes was found 

 to be in a very confused condition, and the work was greatly hampered 

 by lack of abundant and authentic material ; a lack, however, which it 

 was in a large measure possible to overcome through the great generosity 

 of numerous botanists in different parts of the world. But for the pur- 

 pose of further study and for the more intelligent determination of 

 ranges a great deal of material of the genus should be collected. The 

 genus has been so little understood that it seemed more than usually 

 desirable to base information regarding the ranges merely on actual 

 specimens or reproductions examined rather than on published ac- 

 counts. For habitat the labels give almost no data, and except in a 

 few cases there were not specimens enough to form satisfactory con- 

 clusions as to the dates of flowering and fruiting, so that no mention 

 of these subjects has been made. It is hoped, however, that such 

 attention in the field will be accorded this interesting genus that the 

 knowledge of all these matters may be supplied. 



The species have proved to be almost entirely lacking in constant 

 technical characters, so that it has seemed artificial to maintain many 

 of the earlier ones in an independent rank. The genus thus con- 

 tains several complex groups of interrelated types, the study of a con- 

 siderable amount of material of which shows them to intergrade very 

 strongly with each other. It is certainly very undesirable to attempt 

 to distinguish species upon the basis of mere leaf and habital varia- 

 tions. Therefore in treating the genus it has been the plan to make 

 the species stand for something definite, at least, so that they may 

 represent an aggregation of variations more like each other than like 



