DEPENDENT PLANTS 



107 



taches itself to another plant, the dod- 

 der dies away at the base and becomes 

 wholly dependent. It produces flowers 

 in clusters and seeds itself freely 

 (Fig. 133). 



Parasites and Saprophytes. — A plant 

 that is dependent on a living plant or 

 animal is a parasite, and the plant or 

 animal on which it lives is the host. 

 The dodder is a true parasite ; so are 

 the rusts, mildews, and other fungi that 

 attack leaves and shoots and injure 

 them. 



The threads of a parasitic fungus 

 usually creep through the intercellular 

 spaces in the leaf or stem and send 

 suckers (or haustoria) into the cells 

 (Fig. 132). The threads (or the hy- 

 phae) clog the air-spaces of the leaf 

 and often plug the stomates, 

 and they also appropriate 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 

 hyphae finally grow out of the leaf and produce 

 spores or reproductive cells that an- 

 swer the purpose of seeds in distrib- 

 uting the plant {b. Fig. 132). 



A plant that lives on dead or de- 

 caying matter is a saprophyte. Mush- 

 rooms (Fig. 131) are examples; they 

 live on the decaying matter in the 

 soil. Mold on bread and cheese is an 



d o 



Fig. 132. — A Pa rasitic 

 Fungus, magnified. 

 The mycelium, or 

 vegetative part, is 

 shown by the dotted- 

 shaded parts ramify- 

 ing in the leaf tissue. 

 The rounded haus- 

 toria projecting into 

 the cells are also 

 shown. The long 

 fruiting parts of the 

 fungus hang from the 

 under surface of the 

 leaf. 



