86 



DEPENDENT PLANTS 



0. A mushroom, exam- 

 ple of a saprophytic 

 plant. 



180. The threads of the parasitic fungus usually creep 

 through the intercellular spaces in the leaf or stem and 

 send suckers (or haustoria) into the cells 

 (Fig. 122). These threads (or hyphse) 

 clog the breathing spaces of 

 the leaf and often plug the 

 stomata, and they also appro- 

 priate and disorganize the 

 cell fluids : thus they injure 

 or kill their host. The mass 

 of hyphae of a fungus is called 

 mycelium. Some of the 

 hypha? finally grow out of 

 the leaf and produce spores or reproductive cells 

 which answer the purpose of seeds in distribu- 

 ting the plant (b, Fig. 122). 



181. A plant which lives on dead or decaying 

 matter is a saprophyte. Mushrooms are ex- 

 amples: they live on the decaying matter in 

 the soil. Mould on bread and cheese is an 

 example. Lay a piece of moist bread on a plate 

 and invert a tumbler over it. In a few days it 

 will be mouldy. The spores were in the air, or 

 perhaps they had already fallen on the bread 

 but had not had opportunity to grow. Most 

 plants are able to make use of the humus or 

 vegetable mould in the soil, and to that extent 

 might be called saprophytic. 



182. Some parasites spring from 

 the ground (Figs. 118, 119), as 

 other plants do, but they are para- 

 sitic on the roots of their hosts. 

 Some parasites may be partially 

 parasitic and partially saprophytic. 



119. CoraUorhiza or coral-root, \' '^ \ - T 



showing the mycorrhiias. Many (pcrhaps most) of these root- 



