326 FUNGI —PLANTS THAT LACK CHLOROPHYLL 
(sim-bl-o'sis, life together: Greek, syn, with; bios, life) 
(Figure 294). 
Lichens are interesting chiefly as representing this peculiar 
interdependence of plants. T^hey have little or no economic 
importance, although in 
the Arctic Regions they 
furnish a supply of food 
for the reindeer. The dye 
litmus is obtained from a 
lichen. 
We close the study of 
the simplest plants with 
the fungi. As in the case 
of the bacteria, men have 
spent their lives studying 
the fungi, especially those 
which cause disease. 
Much has been accom¬ 
plished, but a great deal 
remains to be done in find¬ 
ing out the cure for certain 
fungus diseases, especially 
those that attack vegeta¬ 
bles which we use for food. 
FIELD TRIP FOR THE STUDY OF LICHENS 
After a rainy period, examine trees, rocks, old fences, posts, and 
similar places for lichens. Note the form; the color; the kinds of trees 
having the greatest number of lichens; the trees having the smallest 
number, and the side of the tree having the greatest number. Make the 
same examination during a dry period. 
SUMMARY 
Fungi are plants similar in structure to the algae, but 
they lack chlorophyll. On this account fungi cannot make 
their own food, but always have to use that prepared by 
