xvi Minnesota Plant Diseases. 



FIG. 58. A strangling fungus. Fruiting bodies and spores. Variously 



magnified. After Winter and Brefeld 133 



FIG. 59. Black knot of plum. After Clinton 135 



FIG. 60. Two common types of "burnt-wood" fungi: a dung fungus 

 (Sordariaceae), and a somewhat closely related fungus (of 

 the family Chaetouiiaccae). Magnified. Microphotographs 



by F. K. Butters 137 



FIG. 61. A common cup-fungus growing on sunken sticks and appear- 

 ing abundantly in the spring. Original 140 



-FiG. 62. A single sac and sterile threads from the palisade of sacs of 

 the fungus shown in Fig. 61. Highly magnified. After 



Seavers 141 



FIG. 63. A cluster of cup fungi showing cups just appearing above the 



ground. Original 143 



FIG. 64. A cup fungus on the bark of a fallen tree. Original 144 



FIG. 65. Cup fungus on decaying wood. Original 145 



FIG. 66. Morel fungi. Original 147 



FIG. 67. Saddle fungi. Original 148 



FIG. 68. Truffles. Photograph by F. K. Butters 149 



FIG. 69. Truffles. Fruiting bodies and spores, variously magnified. 



After F. K. Butters. 159 



FIG. 70. Two types of imperfect fungi. Magnified. After Tulasne. .. 151 

 FIG. 71. Smut spores, germinating. Highly magnified. After Brefeld 155 



FIG. 72. Loose smut of wheat. Original 157 



FiG. 73. Spores of rust fungi. Highly magnified. After Ward and 



Carleton 159 



FiG. 74. Spores of rust fungi. Highly magnified. After Tavel 161 



FIG. 75. Cluster-cups of ash-leaf rust fungus, on an ash twig. Mag- 

 nified. Microphotograph by E. W. D. Holway 162 



FIG. 76. Cluster-cup spores from the rust fungus of Fig. 75. Highly 



magnified. Microphotograph by E. W. D. Holway 163 



