REVISION OF THE SPECIES OF MARSHALLIA 



For a number of years certain forms of the genus Marshallia 

 have been appearing in collections made by or coming to the 

 Biltmore Herbarium that have so completely refused to mingle 

 in harmony with representatives of the accepted species, that 

 the writers have ventured to account for them and to rechar- 

 acterize certain of the earlier published species and varieties 

 with which they may have been confounded. The species pro- 

 posed by Rafinesque 1 and Bertol 2 have not been identified, nor 

 have we succeeded in finding authentic specimens with which to 

 associate the names. 



The writers gratefully acknowledge the assistance accorded 

 them by Prof. G. Macloskie, of Princeton University ; Dr. Charles 

 Mohr, of Asheville, N. C. ; Dr. Henry Kraemer, of the Philadel- 

 phia College of Pharmacy ; Mr. William M. Canby, of Wilmington, 

 Delaware ; Dr. J. K. Small, of the New York Botanical Garden ; 

 Prof. William Trelease, of the Missouri Botanical Garden ; 

 Dr. B. L. Robinson, of the Gray Herbarium of Harvard Uni- 

 versity ; and Dr. J. N. Rose, of the United States National 

 Museum, for information concerning certain specimens or for 

 the use of the valuable collections under their charge. 



KEY TO THE SPECIES 



Scales of the involucre with subulate or attenuate tips . . . M. graminifolia 



Scales of the involucre with acute or obtuse tips. 



Chaff of the receptacle spathulate M. obovata 



Chaff of the receptacle slightly if at all dilated at the 

 summit. 



Corolla tubes swollen at the throat. 



Leaves thin, usually less than I2 cm long . . . . M. trinervia 

 Leaves firm, frequently 2-2. 5 dm or more long . . M. grandiflora 

 Corolla tubes not swollen at the throat. 



Pappus scales i-2 mm long, species occurring east of 

 the Mississippi. 



Leaves i.5~3 cm wide, ovate-lanceolate M. mohri 



Leaves narrower, linear-lanceolate M. ramosa 



Pappus scales 2-4 mm long, species occurring west of 



the Mississippi M. ccespitosa 



1 New Flora, 4:77, 1836. 



2 Mis. Bot., 15 : 22, 1S56. 

 Issued April 8, igoi. (3) 



