Diseases of Plants 287 



Lower forms of plant life. But all about us are many 

 sorts of plants that never produce flowers and seeds. 

 The simplest form of these seedless plants have no roots, 

 stems, or leaves. Some are so small that we cannot 

 see them with the naked eye. Many of these seedless 

 plants have no green coloring matter and hence are not 

 able to make their own sugary foods. These colorless 

 (not green) and seedless little plants are all about us, 

 and they affect, our crops in so many ways that we need 

 to learn about them. 



Plants without green coloring matter. The fungi 

 (singular, fungus) are a great group of colorless and 

 seedless plants. Mushrooms, puffballs, molds, and the 

 bracket fungi (found on trees) are members of this 

 group. Although some are quite large, they are all 

 composed of single filaments of cells or groups of such 

 filaments and have no leaves, stems, roots, or flowers 

 and no special conducting vessels within them. The 

 fungi produce great numbers of small spores that, when 

 scattered abroad, start the new plants. 



The yeasts and bacteria are other examples of color- 

 less and seedless plants. In these the plant consists of 

 but a single cell. The yeasts multiply by budding ; the 

 bacteria, by simple division. Some of the yeasts and 

 bacteria produce spores that can withstand drying and a 

 high temperature without injury. Some vegetables are 

 difficult to can so that they will keep, because they carry 

 bacterial spores that are killed only by steaming under 

 pressure or by a long period of boiling. 



Parasites. A colorless plant cannot make its own food, 

 but, like an animal, it must have food that is already 



