THE NORTH AMERICAN SPECIES OF OPLISMENUS. 



By A. S. Hitchcock. 



INTRODUCTION. 



This genus of grasses comprises four species in the American 

 tropics and about as many in the tropics of the Old World. All 

 are shade plants with broad flat blades and strongly dorsiven- 

 tral, creeping sterile shoots. Nearly all the species have been 

 referred to the four genera Panicum, Oplismenus; Orthopogon, and 

 EcJiinocMoa, which fact accounts for much of the extended synonymy. 

 One species is found in the United States along the coast from North 

 Carolina to Florida and Texas. 



The text figures are natural size. 



DESCRIPTION OF THE GENUS AND SPECIES. 



OPLISMENUS Beauv. 



T o 



Oplismenus Beauv. Fl. Owar. 2: 14. pi. 68. f. 1. 1809. A single species, 0. africanus, 

 is described and figured. The name is occasionally spelled Hoplisvienus. 



Orthopogon R. Br. Prodr. Fl. Nov. Holl. 194. 1S10. Four species are described 

 and two, panicum hirtellum and P. burmanni, are mentioned in a note as belonging to 

 the genus. The first, 0. compositus, is accepted as the type because it is based 

 on a Linnaean species (Panicum compositum L.), while the other three species are 

 described as new. 



Hekaterosachne Steud. Syn. PI. Glum. 1: 118. 1854. A single species, H. elatior, 

 from New Zealand is described. Cheeseman ' refers this to Oplismenus. 



Hippagrostis Kuntze, Rev. Gen. PI. 2: 776 1891. Kuntze accepts Hippagrostis 

 Rumpf. 2 The type is Panicum burmanni Retz. 



DESCRIPTION. 



Usually weak, freely branching, creeping annuals or perennials with erect or 

 ascending flowering shoots, flat, thin, ovate or lanceolate, asymmetric blades, and one- 

 sided spikelike racemes along a main axis. Spikelets terete or somewhat compressed 

 laterally, subsessile, in pairs or solitary in two rows on one side of a narrow, scabrous or 

 hairy rachis. Glumes subequal, emarginate or entire, the midnerve extending into 

 an awn, that of the first longer. Sterile lemma exceeding the glumes and fruit, notched 

 or entire, mucronate or short-awned, inclosing a hyaline palea. Fruit elliptic, acute, 

 the lemma very convex or boat-shaped, the firm margins clasping the palea, inrolled. 



The genus consists of four species in the American tropics and about as many more in 

 the tropics of the Old World. One of the American species has been introduced. 



The species are shade-loving, growing on the forest floor or in shade of orchards and 

 groves, often forming a carpet. 



1 Man. New Zeal. Fl. 849. 1906. 



2 Herb. Amboin. 6: 14. pi. 5./. 3. 1750. 

 168000—20 2 123 



