AbstractA novel technique has been developed to inoculate the outer epidermal cells of coleoptiles of barley, oats and wheat with S. nodorum. Using this technique, which results in a large number of attempted penetrations, the composition of the material deposited at unsuccessful penetration sites in these cereals have been compared. Although the deposits reacted in a similar manner with some histochemical reagents (ammoniacal silver solution, Coppick‐Fowler reaction, p‐nitrobenzene tetrafluoroborate and Coomassie brilliant blue R250) marked differences occurred between the reactions sites formed by barley and wheat and by oats with other stains (bromophenol blue, nile blue sulphate and Toluidine blue). Chemical treatments used to delignify tissue also revealed differences in these reaction sites. It is concluded that although the reaction sites share some similar components there are significant differences in their chemical struct