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. Syntherisma filiformis (.) 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. Leptotoma 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: Panicum cognatum Schult. 
Leptoloma Chase, Proc. Biol. Soc. Washington 19: 191. 1906. The type is 
designated. 
The only species found in our country is Leptoloma cognatwm 
(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 
United States. 
Type species: Panicum dimidiatum UL. 
Stenotaphrum Trin., Fund. Agrost. 175. 1820. A single species is mentioned, 
S. glabrum Trin., based on Rottboellia dimidiata 1., which in turn is based on 
Panicum dimidiatum L, 
