Vol. XXVIII, pp. 25-44 March 12, 1915 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



ANDROPOGON HALEPENSIS AND ANDROPOGON 



SORGHUM. 



BY CHARLES V. PIPER. 



Johnson-grass, Andropogon halepensis (L.) Brot., and sorghum, 

 A. sorglmm (L.) Brot., are nearly always treated as distinct 

 species in botanical works. Along with this botanical treat- 

 ment, however, the statement is frequently made that the latter 

 is believed to be derived from the former under cultivation. 

 This conclusion is usually accredited to Hackel but without 

 due consideration to what that botanist actually wrote. It is 

 true Hackel considered that there was but one botanical species 

 involved, namely, Andropogon sorghum, but consisting of two 

 subspecies, A. sorghum halepensis, wild perennial or rarely 

 annual plants with the spikelets readily deciduous at maturity, 

 and A. sorghum sativus mostlj^ cultivated, annual or in the 

 tropics sometimes perennial plants, with the spikelets persistent 

 at maturity. While Hackel regarded the cultivated plants as 

 having been derived by cultivation from A. sorghum halepensis, 

 he expressly writes that he does not believe that the wild va- 

 rieties with rootstocks were at all concerned with the cultivated 

 sorghums, but that the latter originated from such wild varieties 

 as cffusus, virgatus and aethiopicus, all of which are devoid of 

 rootstocks. 



A more satisfactory treatment of the plants in question is to 

 consider them two distinct species — Amlropogon halepensis, per- 

 ennial plants possessing rootstocks, and Andropogon sorghum, 

 annual plants (perennating in frostless regions) without root- 

 stocks. The facts of distribution as well as those concerned 

 4— Proc. Biol. Soc. Wash., Vol. XXVIII, 1915. (25) 



