CONTRIBUTIONS FROM THE GRAY HERBARIUM OF 

 HARVARD UNIVERSITY.— NEW SERIES, No. XLI. 



By Sidney F. Blake. 



Presented by B. I.. Robinson 14 May, 1913. Received 12 June, 1913. 



I. A REDISPOSITION OF THE SPECIES HERETOFORE 

 REFERRED TO LEPTOSYNE. 



Among the numerous genera of the Hehanthoid Compositae scarcely 

 any has had a more involved history than the genus Coreopsis L., 

 its synonymy embracing more than a score of generic names. On the 

 one hand closely allied to the still larger genus Bidens, and perhaps 

 not clearly separable from it, it is related on the other to various smaller 

 and much more distinct genera. One group of about a dozen species, 

 characterized by fertile rays and the presence of an annulus on the 

 tube of the disk-flowers, has by many authors been kept distinct under 

 the name Leptosyne DC, but by Bentham and Hooker,^ Hoffmann,^ 

 and more recently by Hall,^ has been reduced to Coreopsis, apparently 

 with justice. In habit, involucre, and achenes its members are closely 

 similar to various species of genuine Coreopsis; and while most of the 

 species have a thickened hairy annulus at base of throat in the disk- 

 corollas, this is glabrous in some species * and entirely absent in others,^ 

 while the rays although usually fertile are sometimes sterile or neutral 

 in the section Pugiopappus; so that in the absence of any quite con- 

 stant diagnostic character and because of the general very close simi- 

 larity, it seems advisable to follow the authorities aboA^e mentioned 

 in referring the genus definitely to Coreopsis. 



The genus Coreocarpus Bentham, on the other hand, although made 

 a section of Leptosyne by Gray and included by Hoffmann in his section 

 Leptosyne of Coreopsis, departs in its isomorphic involucral scales so 



iGen. PL ii. 385 (1873). 



2 In Engler & Prantl, Nat. Pfl. iv. Ab. 5. 243 (1890). 



3 Univ. Calif. Pub. Bot. iii. 139 (1907). 



4 L. maritima, L. gigantea. 



5 L. mexicana, L. insularis; and Electra has no annulus. 



