Minnesota Plant Diseases. 243 



basidia in a palisade layer similar to that of the Stereum wood 

 rot. The fruiting bodies are very easily recognized, but the rot- 

 ting wood is even more characteristic. In the early stages of 

 rot there are seen whitish, circular or oval patches in the wood, 

 which are more or less permeated with the mycelium of the fun- 

 gus. In these patches the wood is quickly disintegrated while 

 the wood dividing the patches remains very hard. In later 

 stages the whitish patches become hollow by the complete de- 

 struction of the wood and a longitudinal section of such a timber 

 would show a net-like arrangement of wood enclosing the de- 

 cayed patches. Around these holes can be seen a lining of 

 the whitish mycelium. Finally the walls between the holes also 

 disintegrate and the entire timber crumbles. 



The smothering fungus of seedlings (Thclcphora tcrrestris 

 Elirh. and T. laciniatuiii Pcrs.). One often finds, particularly in 

 damp situations at the bases of young saplings of hard maples 

 and other trees, blackish, soft, leathery masses forming an 

 irregular ring around the base of the stem just above the 

 ground. At first sight they may seem shapeless and they are 

 not at all conspicuous objects. A close examination shows 

 them to be composed of numerous shelves, like the shelf fungi, 

 and usually hemispherical in shape, jutting out from the main 

 mass of the fungus. (T. terrestris.) Another species, Thele- 

 phora laciniatum. forms masses with irregular projections 

 which vary from club- or tooth-shaped to fan-like in form and 

 are usually combined into a rosette. If one examines the under 

 surface of these shelves or clubs with a microscope one finds 

 there numerous dark-colored spores with very rough outer 

 walls. These spores are produced in fours on basidia which 

 occur in palisades in the way usual for the palisade fungi. 



These fungi are not truly parasitic but derive their nourish- 

 ment from matter in the soil. They have nevertheless been 

 reported as dangerous to forest culture on account of their be- 

 havior toward seedlings. The fruiting body starts as a shape- 

 less mass lying on the ground and when it conies in contact 

 with any upright support it grows upward a short distance and 

 then produces the projections of the mature form described 

 above. If this support happens to be a seedling the latter may 

 become completely engulfed and destroyed. As this fungus is 



