GENERA OF GRASSES OF THE UNITED STATES. 187 
Perennial or rarely annual grasses, with short, flat, stiff blades, 
numerous stiff, slender, divergent spikes loosely scattered along the 
upper part of the culm, or sometimes aggregate toward the summit, 
the spikes often deflexed at maturity. Species 10, nearly all Amer- 
ican; 3 species in the southeastern United States. 
Type species: Andropogon ambiguus Michx. 
Gymnopogon Beauv., Ess. Agrost. 41, pl. 9, f. 3. 1812. Beauvois mentions one 
species, Andropogon ambiguus Michx., which is figured. In the description of 
the plate the name given is Gymnopogon racemosus. 
Alloiatheros Ell., Bot. S. C. and Ga. 1: 146. 1816. This name is casually 
mentioned by Hlliott in the deseription of Andropogon ambiguus: “1 once in- 
tended to insert it as a distinct genus under the name of Alloiatheros, from the 
dissimilarity of its awns, not only in position but in figure.” 
Anthopogon Nuit., Gen. Pl. 1: 81. 1818. Based on Andropogon ambiguus 
Michx., which name Nuttall changes to Anthopogon lepturoides. 
The spikelets are usually 1-flowered and awned, but in Gymnopogon 
chapmanianus Hitche., of Florida, they are 2 to 4 flowered and awn- 
less. This species shows in its spikelet characters a transition to 
Leptochloa, but in habit it closely resembles the other two species of 
the United States. In G@. foliosus (Willd.) Nees, of Porto Rico and 
South America, the rudiment bears two long awns. Our species are 
perennials, with an inflorescence of scattered spikes. 
Our commonest species is Gymnopogon ambiguus (Michx.) B.S. P. 
(fig. 111), found in sandy soil from New Jersey to Missouri and south 
to Florida and Texas. Another species, G. brevifolius Trin., grows 
from New Jersey to Florida. This species differs from the preced- 
ing in having the rachis spikelet bearing only along the upper half. 
The species have no agricultural importance. 
93. CHLoRIS Swartz. 
Spikelets with 1 perfect floret, sessile, in two rows along one 
side of a continuous rachis, the rachilla disarticulating above the 
glumes, produced beyond the perfect floret and bearing 1 to several 
reduced florets consisting of empty lemmas, these often truncate, and, 
if more than one, the smaller ones inclosed in the lower, forming a 
usually club-shaped rudiment; glumes somewhat unequal, the first 
shorter, narrow, acute; lemma keeled, usually broad, 1 to 5 nerved, 
often villous on the callus and villous or long-ciliate on the keel or 
marginal nerves, awned from between the short teeth of a bifid apex, 
the awn slender or sometimes reduced to a mucro, the sterile lemmas 
awned or awnless. 
Perennial or sometimes annual, tufted grasses, with flat blades and 
two to several often showy and feathery spikes aggregate at the 
summit of the culms. Species about 60, in the warmer regions; 15 in 
the southern United States. 
Type species: Agrostis cruciata T. 
Chloris Swartz, Prod. Veg. Ind. Oce, 25. 1788. Swartz describes five species, 
C. cruciata, C. ciliata, C. petraea, C. polydactyla, and C. radiata, all from the 
