26 Proceedings of the Biological Society of Washington. 



with the origin of the cultivated sorghums are consistent with 

 this treatment. 



In reaching the conclusions in the classification here pre- 

 sented the writer has had the advantage of studying many of 

 the forms under cultivation, besides all the herbarium material 

 in this country, and that at Kew and at Berlin. The location 

 of each specimen studied is indicated by giving in parentheses 

 the name of the herbarium to which it belongs. 



Key to the Subspecies of Andropogon halepensis . 



Stems relatively slender, rarely over 7 mm. in diameter; leaf blade less 

 than 30 mm. broad; rootstocks abundant. 

 Panicle not loose and drooping. 



Awns present A. halepensis. 



Awns wanting A. halepensis anatherus. 



Panicle loose and drooping. 



Awns present A. halepensis miliformis . 



Awns wanting A. halepensis muticus. 



Stems stout, 10-30 mm. in diameter; leaf blades 3-5 cm. broad; root- 

 stocks few. 



Spikelets 4 mm. long A. halepensis propinquus. 



Spikelets 4.5-5 mm. long . A. halepensis siamensis. 



Andropogon halepensis (L.) Brot. 



Holcus halepensis L. Sp. PI. 1047. 1753. Based on the description and 

 figure of Plukenet (Aim. 176. t. 32 f. 1. 1696). Plukenet's specimen 

 was from Bobart, but its source is not indicated except by the descrip- 

 tive term halepense, from which it may be surmised that Aleppo or 

 Haleb, Asia Minor, is its original source. Plukenet's crude figure 

 shows an awned grass, which in the absence of any evidence to the 

 contrary may well be Johnson-grass. 



Andropogon arundinaceus Scop. Fl. Carn. Ed. 2, 2:274. 1772. Specimen 

 from a field in " Tergestino," Carniola. Scopoli, however, cites older 

 polynomial synonyms of Linnaeus and of Scheuchzer. 



Andropogon halepensis Brot. Fl. Lusit. 1:89. 1804. 



Sorghum halepense Pers. Syn. 1:101. 1805. 



Sorghum dubium Koch, Linnaea 21:443. 1848. Original specimens from 

 Caucasia, found growing with A. halepensis. The plants were diseased, 

 being infested with a smut, which probably accounts for the difi"erences 

 noted by Koch. 



Andropogon dubitatus Steud. Syn. PI. Glum. 1:394. 1854. A change of 

 name for the preceding on account of the earlier Andropogon dubius 

 Kunth. 



Sorghum halepense latifolium Willk. & Lange Prodr. Fl. Hisp. 1:48. 1861. 



Andropogon sorghum halepensis genuiniis Hack, in DC. Monogr. Phan. 

 6:502. 1889. 



