A NEW SMUT ON SORGHUM HALEPENSE NEES. 



By Iltyd Buller Poi.i^ Evans, M.xA.., B.Sc. F.L.S. 



[Plate 19.) 



Towards the latter jxirt of February, 191 5. Mr. J. A[. Sim, 

 of Maritzliurg-, Natal, sent me for identification a smut on the 

 common Johnson grass (Sor</liuiit halc/'ciisc Nees ) of Natal. 



On examination the smut proved to be an undescribed 

 species of Sorosporimii, and I propose to describe it as Soros- 

 porhim Siiiiii Pole Evans, n.s]). 



The description is as follows : — 



Sori attacking and destroying the entire inflorescence while 

 still enclosed in the sheathing blade, elongated np to 5-7 cm. long 

 and 1-2 cm. broad, black, becoming powdery, covered at first 

 with a rather thick white or isabelhne membrane; spore balls 

 subglobose or ellipsoid, black, (;)0-i5o /x diam. ; spores globose or 

 subglobose. olivaceous or olivaceous-brownish, very delicately 

 echinulate, 12-13 //. diam. 



(Jn Audropogoii halcpcnsis Brot., var. cffiisiis Stapf.. 

 Maritzbin-g, Natal, February 23rd, 1915. 



Sorosporium Simii. — Soris inflorescentiis' evolutis easque 

 omnino destruentibus. partim vagina foliari inclusis, elongatis 

 usque ad ^-j cm. longis et i-J cm. latis, atris, i)ulverulentis, mem- 

 brana albida vel isabellina crassiuscule primo tectis ; glomerulis 

 subglobosis vel ellipsoideis. atris 60-150 ft diam. ; sporis globosis 

 vel subglobosis olivaceis vel olivaceo-brunneis, tenuissime echinu- 

 latis, 12-13 jx diam. 



Hab. in inflorescentia Andrupoyoiiis lialcpciisis Brot., var. 

 ejfusi Stapf., leg. J. M. Sim, Maritzburg, Natal, February 23rd, 



This grass is now referred to the genus Sorgliiiui, and is 

 known botanically as Sorgliiiin halcpcnsc Nees. It closely resem- 

 bles the grass known as Sotidan grass (Andropogon sorghum 

 siidaneusis Piper) in habit of growth, in foliage and seed, but is 

 a perennial, whereas Soudan grass is an annual. 



Soudan grass, which is a native of Tropical North Africa, 

 has recently been attracting a lot of attention in America and 

 this country as a hay grass, and should it justify its cultivation 

 on a large scale, as it at present gives every promise of doing, 

 the parasites that occur on Johnson grass should be taken into 

 consideration. 



The object of this note is therefore to draw attention to the 

 fact that a dangerous snuit occurs naturally on Johnson grass 

 in South Africa, and in the opinion of the writer it seems highly 

 probable that this smut may attack Soudan grass unless due 

 precautions are taken. 



An opportunity of definitely testing the effect of Sorospo- 

 rium Simii on Soudan grass has not yet arisen, but it is hoped 

 that experiments in this dnrection may be undertaken during the 

 next season. 



The ni.ere fact that Johnson grass is a perennial suggests 



