218 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 



Syntherisma ischaemum (Schrad.) Nash (Digitaria humifusa 

 Pers., Panicum glabrum Gaud.), also introduced, is darker green and 

 glabrous, and has dark pubescent spikelets, the first glume wanting. 

 This is a common weed in lawns. Syrtfherisma fiUfo?*mis (L.) Nash 

 is an erect native annual with erect racemes, the rachis not winged. 

 Several other species are found in Florida. Nearly all the species of 

 Syntherisma are weedy grasses or tend to become weeds. 



For a revision of the species of Syntherisma found in the United 

 States, see Nash, Bull. Torrey Club 25: 289-303. 1898. 



111. LEPTOLOMA Chase. 



Spikelets on slender pedicels; first glume minute or obsolete; sec- 

 ond glume 3-nerved, nearly as long as the 5 to 7 nerved sterile lemma, 

 a more or less prominent stripe of appressed silky hairs down the 

 internerves and margins of each, the sterile lemma empty or inclos- 

 ing a minute nerveless rudimentary palea; fertile lemma cartilagi- 

 nous, elliptic, acute, brown, the delicate hyaline margins inclosing 

 the palea. 



Perennial branching grasses, with brittle culms, felty pubescent 

 at base, flat blades, and open or diffuse panicles, these breaking away 

 at maturity, becoming tumbleweeds. Species four; one in the United 

 States, the others in Australia. 



Type species : Panteum cognatum Schult. 



Leptoloma Chase, Proc. Biol. Soc. Washington 19: 191. 1906. The type is 

 designated. 



The only species found in our country is Leptoloma cognatum 

 (Schult.) Chase (Panicum autumnale Bosc, P. divergens Muhl.) 

 (fig. 131) growing in sandy soil from New England to Florida ^and 

 from Minnesota to Texas. This genus differs from Syntherisma 

 chiefly in the form of the inflorescence, being an open panicle rather 

 than an aggregation of slender spikes. It is of no economic impor- 

 tance. 



112. STENOTAPHRUM Trin. 



Spikelets embedded in one side of an enlarged and flattened corky 

 rachis disarticulating at maturity, the spikelets remaining attached ; 

 first glume small ; second glume and sterile lemma about equal, the 

 latter with a palea or staminate flower ; fertile lemma chartaceous. 



Creeping stoloniferous perennials, with short flowering stems, 

 rather broad and short obtuse blades, and terminal and axillary 

 spikes. Species about five ; islands of the Pacific ; one in the southern 

 TJnited States. 



Type species : Panicum dimidiatum L. 



Stenotaphrum Trin., Fund. Agrost. 175. 1820. A single species is mentioned, 

 8. glabrum, Trin., based on Rottboellia dimidiata L., which in turn is based on 

 Panicum dimidiatum L. 



