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. Acolorless plant cannot make its own food, 
but, like an animal, it must have food that is already 
