XXIX. SYMBIOSIS IN THE GENUS LOLIUM. 



E. M. Freeman. 



The existence of fungus hyphae in Lolium tanulentwm, L. 

 ■perenne and L. italiciim furnishes interesting relationships be- 

 tween host and parasite. Nothing has as yet been done with 

 the two latter species but the life-cycle of the Lolium temulen- 

 tum fungus is perhaps completely known. There is however 

 no reason for supposing that they differ at all from L. temulen- 

 tum in their life-histories. It cannot be affirmed without reser- 

 vation that the entire life-history of L. temulentum is understood, 

 but it can be affirmed that the yearly life-cycle is known, and 

 that the parasite can live on indefinitely, infecting generation 

 after generation of Lolium plants without spore intervention. 



The facts of the life-history are briefly as follows : certain 

 grains of L. temulentum, varying in number in ordinary com- 

 mercial mixtures of the grains, from 85 per cent, to 98 per cent, 

 of the total number, show a layer of hyphae in the hyaline 

 layer just exterior to the aleurone cells. Occasionally these 

 hyphae penetrate into the endosperm, between the aleurone and 

 starch cells, but never enter them. The fungus does not appar- 

 ently thrive in the endosperm. On the convex side of the grain 

 the hyphae extend almost or quite to the tip of the scutellum but 

 never enter the scutellum from this point. Along the grain 

 groove the hyphae are missing except at the very base where an 

 infection patch exists, from which hyphae can be found penetrat- 

 ing into the base of the scutellum of the embryo and from here 

 to the growing point of the plumule, where a considerable patch 

 of mycelium is developed and remains dormant until the grain 

 germinates. On germination the hyphae keep pace in their 

 growth with that of the growing point and can be found here 

 throughout the remaining life of the plant. The hyphae develop 

 in all of the branches and also in the leaf-bases. The appear- 

 ance in the latter is explained in the similar chemotactic proper- 

 ties of the basal leaf-meristem to those of the stem growing- 

 point. In the young ovaries the hyphae permeate the nucellus 

 and here develop luxuriantly. They are pushed back by the 



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