OnOBANCHE AS A PARASITE IN BIHAR 



BY 



F. J. F. SHAW, D. Sc. (Lond.), A.R.C.kS., F.L.S., 



Second Impenal Mycologist. 



(Heceived for publication on •21st ISlarch, 1917.) 



I. SYSTEMATIC. 



In view of the fact that " tokras " are so widespread in Bihar, and occur 

 on so many different hosts, the present research was commenced to investigate 

 the biology of these parasites and in the hope of discovering whether any 

 method could be devised to lessen the damage which they cause. 



As is well known the parasitic species of Orohanche, known locally as 

 "tokras," are small yellow plaiits from 3-12 inches high with bluish flowers. 

 The stems are thick and succulent and the leaves are reduced to small scales, 

 as is usual in plants of this habit. A very brief experience of this parasite 

 in the field is sufficient to convince one that; there are at least two species, 

 which are common in Bihar. Hooker^ describes eleven species in India, of 

 which the greater number occur in the Himalaya and only three appear to 

 be common in the plains ; these are 0. indica Ham., 0. cernua Lceffl., and 

 0. NicotiancB Wight, the last named is stated to be a common and destructive 

 pest of tobacco in the Deccan, while 0. indica is said to be especially common 

 in mustard throughout the plains of India. Prain^ mentions two species, 

 0. indica Ham. and 0. cernua Loeffi., as being present in Bihar ; he states that 

 0. cernua is rare, and occurs on Brassicas, and that 0. indica is the common 

 pest of mustard, tobacco, Brassicas, etc. The presence of two bracteoles to 

 each flower, and the fact that in 0. indica the flowers are larger and not so 

 closely crowded together as in 0. cernua, are the distinguishing charatjters 

 between the two species (Plate I. figs. 1 and 2 ; Plate II, fig. 3.). 



The results of the observations recorded in the present paper differ 

 somewhat from the facts given by Prain, and coincide more nearly with 



1 Hooicer, Flora of British India, \u\. IV, 1885. 



2 Prain, Bengal Plants, 1903. 



