128 REPRESENTATIVE PLANTS 



fungi. How may this plant have gained a foothold on the 

 host? Consult reference books for methods of reproduction. 

 Reference reading. Read about the damage to growing 

 croi)s caused by these plants and give the remedies recom- 

 mended. Consult the government bulletins which give a 

 large amount of information about fungus diseases and 

 spraying for prevention. Many details of reproduction, life 

 history, and other important features must be left to the in- 

 dividual teacher's judgment. 



Type 10. Lichens 



Habitat. The plants may be found by the pupil, growing 

 on trees, fences, old sheds, stones, often almost completely 

 covering the objects on which they grow. 



Appearance. It is well, if x^ossible, to have a plentiful 

 supply of three common forms : foliose or leaflike ; crusta- 

 ceous or encrusting ; and fruticose or bushy form. In the 

 specimens presented determine to which of the above groui)S 

 each belongs, also upon what the plant is found; observe the 

 form assumed by the entire growth (lichens often form, 

 for example, beautiful rosettes). Examine carefully and de- 

 termine how the plant is attached to the object upon which 

 it grows. Make careful drawings i-howing the three forms, 

 natural size. 



Experiment. Take a dry lichen, observe its color, and 

 then thoroughly soak it. What change in size and color 

 takes place ? Recall, if you have seen it, the effect of rain 

 on tree lichens, also on a grass plot after a warm shower. 



Structure. Study with (Ip) or (hp) prepared specimens 

 of a lichen to show its real structure. Observe the inter- 

 woven mass of white threads. How do they resemble the 

 forms already studied among the algae and fungi ? Observe, 

 in particular, the layer of greeyi cells mixed with the white 

 j&laments. What plant do they resemble ? In fact, these 



