298 Holm — Studies in the Cyperacew. 



Art. XXXIII. — Studies in the Cyperacew ; by Theo. Holm. 

 VI. Dichromena leucocephala Vahl, and D. latifolia 

 Baldw. 



The genus Dichromena was established by Michaux (]. c. 

 xiii) upon the plant which he named D. leucocephala, on 

 account of the snow-white inflorescence, while the generic 

 name, derived from St? and ^/cxwyita, should merely refer to the 

 partly discolored involucre. Xo other name could be more 

 suitable for this singular species, but our plant has, neverthe- 

 less, met with the same fate as so many of the other Xorth 

 American plants, viz : to get its name changed and to become 

 confounded with totally different species. Professor X. L. 

 Britton, for instance, changed its name to Dichromena cepha- 

 lotes, while Professor A. S. Hitchcock (1. c. ii) suggested the 

 name D. colorata, since he thought that Linnaeus had this plant 

 before him when he described his Schoemcs color atus (1. c. vii). 

 It is not, however, likely that this last change of name will 

 hold good either, for two reasons : first, that Lin use ns would 

 hardly have called our discolored Dichromena " colored ;" and 

 second, because the Linnean diagnosis does not prove that 

 these two plants are really the same. 



In regard to the specific name " coloratus," Linnseus did not 

 use this term for discolored organs, but he used " variegatus" 

 for instance (1. c. v) " Arundo indica variegata," " G-ramen 

 paniculatum aqn. phalaridis sera, folio variegato," and "Agri- 

 folium foliis ex albo variegatis," which plants exhibit the same 

 discoloration as our Dichromena. Furthermore, in his Phil- 

 osophia botanica (1. c. ix) Linnseus employed the terms 

 "albicans" and " pallescens " for such organs as are whitish 

 or pale green, viz: "Abrotanum cauliculis albicantibns," etc., 

 besides that he named a species of Schoenus " niveus" (1. c. x) 

 in contrast to his Schcemts u color at-us" ! These two species 

 are now generally recognized as Kyllinga triceps and K. mon- 

 ocephala, of which the first one is described by Kunth (1. c. iv) 

 with " squamis hyalino-albidis " (niveus), while the other species, 

 K. monocephala, has the same organs ''purpureo-pnnctulatis " 

 (coloratus). 



There are, furthermore, if we examine the diagnosis of 

 Schoenus coloratus, some points which seem to show that Lin- 

 naeus did not intend to describe our Dichromena / he says, as 

 follows : " Schoenus coloratus, culmo triquetro, capitulo subro- 

 tundo, involucro longissimo piano variegato." This last char- 

 acter may suit very well for a Dichromena, although the 

 involucre of some species of Kyllinga is known, also, to show a 



