AUTOBASIDIOMYCETES 477 



the lower, or lamellar, portion of the pileus, the cap is quickly raised 

 and the veil broken at the margins of the pileus, with the gradual 

 expansion of the upper portion of the plant. This general form of 

 development apparently maintains in most angiocarpic Agaricaceae 



Fig. 238. Armillaria mellea: Basidial Surface. (After Hartig) 



which possess a veil only. Differences occur, however, with regard 

 to the time of differentiation, position of the forming lamellae, the 

 stem, veil, etc. 



XIV. EUROPEAN ROOT DISEASE OF ALFALFA AND 

 OTHER PLANTS 



Rhizoctonia Medicaginis De C. 



Frank, A. B. Die Pilzparisitaren Krankheiten der Pflanzen, /. c, pp. 514-518. 



Kuhn, J. Die Krankheiten der Kulturgewachse, /. <,., p. 245. 



Tulasne, L. R. and C. Rhizoctonia. Fungi Hypogsei, I.e., pp. 188-195. 



De Candolle described accurately the root disease of alfalfa 

 (Medicago sativa) in 1815, and gave to the violet fungus pro- 

 ducing the disease the name above indicated. The fungus had 

 previously passed under another name, which, however, probably 

 referred to several diverse species. From the subsequent work of 

 Kuhn, Frank, Comes, and others, much additional information has 

 been presented concerning this fungus. Many, however, have re- 

 garded it as closely related to certain sterile fungi found upon 

 the crocus, potato, cabbage, sugar beet, and many other cultivated 



