36 Proceedings of the Biological Society of Washington. 



haJepensis. For the same reason there exists doubt as to the identity of 

 Andropogon avenaceus H B K. as that is based on specimens from Vene- 

 zuela, from wliich country only specimens of Andropogon halepensis exist 

 in the U. S. National Herbarium. Trachypogon avenaceus Nees was used 

 with especial reference to specimens from Brazil where ^^msms is abundant, 

 and therefore there is not the same reason to doubt Hackel's disposition 

 of this binomial. 



Culms tall, 2-3 meters or more, stout; leaves flat, 2-4 cm. broad, bright 

 green; panicle large, 30-50 cm. long, loose, oblong to ovate or pyramidal, 

 somewhat nodding; branches slender, subverticillate in 5 to 8 whorls, 

 ascending or sometimes spreading, the lower ones half as long as the 

 panicle, pilose at the nodes; lower glume of fertile spikelet elliptic-lanceo- 

 late, 6-7 mm. long, 2 to 2.5 mm. wide, 7-nerved, slightly coriaceous, 

 somewhat constricted at base, straw-colored and falling easily when 

 mature, covered with a white or fulvous appressed pubescence or glabrate 

 on the back; awns 7-9 mm. long, but short-awned and awnless forms 

 also occur; sterile spikelets narrowly lanceolate, often purplish, nearly 

 glabrous, strongly nerved, 6-7 mm. long, on shorter hairy pedicels; 

 caryopsis brownish-yellow, obovoid, flattened, 3 mm. long. 



This subspecies is apparently restricted in Africa to the humid region 

 surrounding the Gulf of Guinea. In America it occurs in Brazil and 

 Cuba, probably introduced with slaves. The type is Willdenow's original 

 specimen of Andropogon arundinaceus which came from Guinea. We have 

 not seen this specimen but follow the conclusion of Hackel who bases 

 upon it his Andropogon sorghum effusus subvariety aristatus. 



The following specimens have been examined: 



Spikelets with Long Awns (subvar. aristatus Hackel). 

 S. Thome, Moller No. 150, June, 1885 (Kew); Kamerun, Ossidinge, 

 Dr. Mansfeld No. 8 (Berlin); Bomma (Boma), Congo River, No. 136, 

 5-9-74 (Berlin); Spanish Guinea Hinterland, Nkolentangan, Alcu, 

 G. Tessmann, No. 257, March 5, 1908 (Berlin); Spanish Guinea Hinter- 

 land, Fan, O. Tessmann, No. 93, in 1907 (Berlin); Brazil, Burchell, No. 

 1632 (Cambridge); Pernambuco, Gardner No. 1177 (Cambridge); 

 Brazil, Sao Joao del Ray, Minus. Dorsett No. 309b. under cultivation 

 (Washington); Brazil, Lavras, Minas, Dorset 213b (Washington). 



Spikelets with Short Awns (subvar. submuticus Hackel). 



Brazil, Blanchet No. 1962 (Washington); Brazil, near Rio Janeiro, 

 Wilkes Exped. (Washington); Fernando Po, Mann, No. 114, Dec. 1859 

 (Kew); Togo, Misanohe, Baumann, No. 151, 5 IV 94 (Berlin); Nupe, 

 Niger Banks, Warier No. 170 in 1858 (Berlin); Mav-Tchufi, Kamerun, 

 C. Ledermann No. 4180 (1909) (Berlin). Nun mouth of Niger, Vogel 

 No. 50 (Kew). The last specimen is peculiar in that the fully mature 

 spikelets are black, and indurated. 



Spikelets Without Awns. 

 Nupe, Niger Banks, Barter No. 1379 (Kew): Gabon, French Kongo, 

 Soyaux No. 284, 20 | 4 j 1881 (Kew) (Berlin); Gold Coast, W. H. 



