36 HITCHCOCK: A PECULIAR SPECIES OF LASIACIS 



section of Panicum and gave to it the name Lasiacis, meaning 

 woolly tip. The aspect of the species is so distinct and the 

 technical spikelet characters so pronounced that the present 

 writer elevated this section to the rank of a genus in 1910.^ 

 Lasiacis includes 13 species ranging from Mexico and the West 

 Indies to Paraguay, one species entering the United States in 

 semitropical Florida. 



Lasiacis ruscifolia (H. B. K.) Hitchc. & Chase {Panicum com- 

 pactum Swartz), is more variable and has a wider range than 

 the other species. In an account of the genus as represented 

 in the West Indies^ occurs the following note: 



"In all the Trinidad specimens the spikelets contain a second 

 sterile lemma, a character not found in any other species known 

 to us. This second sterile lemma equals the first, contains a 

 hyaUne palea, and infolds the fruit rather more closely than the 

 sterile lemma commonly does in other species. The fruit borne 

 one joint higher on the rachilla consequently faces in the direc- 

 tion opposite to the one in Paniceae, that is, the palea side of 

 the fruit faces the second instead of the first glume." 



A reconsideration of the group leads me to the conclusion 

 that we have here a distinct species, for not only is there this 

 unusual character of a second sterile lemma but also a distinct 

 geographical range. Of the group to which it had been referred, 

 all the specimens from Trinidad, the lower Orinoco, and eastern 

 Brazil have a second sterile lemma, while outside of this range, 

 that is, north and west, there is but one sterile lemma in all 

 the specimens examined. In other respects, such as shape of 

 blades and panicle, pubescence, shape and size of spikelets, the 

 new species does not dififer from L. ruscifolia from which it has 

 been separated. The specimens of the new species, Lasiacis 

 anomala, agree closely among themselves in all these characters, 

 but also agree with many specimens referred to the more variable 

 species L. ruscifolia. 



The peculiarity of the case under consideration consists in 

 the nature of the single diagnostic technical character, the second 



» Contr. U. S. Nat. Herb. 15: 16. 1910. 



* Hitchcock and Chase. Grasses of the West Indies. Contr. U. S. Nat. Herb. 

 18: 339. 1917, 



