16 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



GENERA HERE EXCLUDED. 



The genus Panicum as accepted by Dalla Torre and Harms a includes 

 a number of groups which in our treatment have been excluded. Of 

 the twelve sections into which Panicum is there divided, the first 

 eleven belong to allied genera, as do Streptostachys and Otachyrium 

 of the twelfth section. Coleataenia Griseb. from South America, 

 included in the twelfth section, is a true Panicum. 



In addition to the groups mentioned above, several species referred 

 by many authors to Eupanicum have been excluded. 



Sacciolepis Nash & has been discussed by Chase. c This genus has 

 been confused with Hymenachne Beauv. on account of the similarity 

 in the form of the inflorescence, which is usually a spike-like panicle. 

 The genus is chiefly distinguished by the saccate second glume and 

 stipitate fruit. 



Lasiacis (Griseb.) Hitchc. (Panicum, section Lasiacis Griseb.), d 

 includes the woody, bamboo-like species with globose spikelets hav- 

 ing a bony-indurated fruit, with a downy tuft at the apex, the palea 

 gibbous above and concave toward the base. The type of this genus 

 is Lasiacis divaricata (L.) Hitchc, based on Panicum divaricatum 

 L., the type of Grisebach's section. 



Panicum uncinatum Raddi e is here excluded from Panicum 

 because of the distinctly different spikelets placed with the back of 

 the fruit turned from the rachis, the narrow, aristate first glume as 

 long as the spikelet, the large boat-shaped second glume beset with 

 divergent, uncinate' spines, the sterile floret large and having a 

 subindurated lemma and palea, the fertile floret about two-thirds as 

 large as the sterile one, the margin of the lemma not inrolled — a com- 

 bination of characters showing a closer approach to Echinolaena than 

 to Panicum. 



Panicum aturense H. B. K./ is also here excluded, differing from 

 Panicum as here limited in having equal glumes exceeding the sub- 

 hyaline sterile lemma and a scarcely indurated fruit, the margins of 

 the lemma thin and flat. 



Panicum tuerckheimii Hack.,0 of which we have seen but a single 

 specimen (Tuerckheim's no. 8618, a duplicate type), is an anomalous 

 species with spikelets in which the first glume is wholly wanting, and 

 in which no rudiment of a palea is found in the sterile lemma. 



The genus Lasiacis and the other species here excluded from 

 Panicum will be separately considered in a subsequent paper. 



<*■ Gen. Siphonog. 13. 1900. «Agrost. Bras. 41. 1823. 



&Britton, Man. 89. 1901. /Nov.Gen.&Sp. 1:103. pi. S3. 1815. 



P Proc. Biol. Soc. Washington 21: 6. 1908. 9 Allg. Bot. Zeitschr. 12: 60. 1906. 

 <*F1. Brit. W. Ind. 551. 1864. 



