150 PLANT STUDIES 
color. It has been stated that this green color is due to 
the presence of a coloring matter known as chlorophyll 
(see 12). The two groups may be spoken of, therefore, 
as (1) green plants and (2) plants without chlorophyll. 
The presence of chlorophyll makes it possible for the plants 
containing it to manufacture their own food out of such 
materials as water, soil material, and gases. For this 
reason, green plants may be entirely independent of all 
other living things, so far as their food supply is concerned. 
Plants without chlorophyll, however, are unable to 
manufacture food out of such materials, and must obtain 
it already manufactured in the bodies of other plants or 
animals. For this reason, they are dependent upon other 
living things for their food supply, just as are animals. It 
is evident that plants without chlorophyll may obtain this 
food supply either from the living bodies of plants and ani- 
mals, in which case they are called parasites, or they may 
obtain it from the substances derived from the bodies of 
plants and animals, in which case they are called sapro- 
phytes. For example, the rust which attacks the wheat, 
and is found upon the leaves and stems of the living plant ; 
is a parasite, while the mould which often develops on stale 
bread is a saprophyte. Some plants without chlorophyll 
can live either as parasites or saprophytes, while others are 
always one or the other. By far the largest number of 
parasites and saprophytes belong to the group of low plants 
called fungi, and when fungi are referred to, it must be 
understood that it means the greatest group of plants with- 
out chlorophyll. 
112. Photosynthesis. The nutritive processes in green 
plants are the same as in other plants, and in addition there 
is in green plants the peculiar process known as photosyn- 
thesis (see 25). In plants with foliage leaves, these are 
the chief organs for this work. It must be remembered, 
however, that leaves are not necessary for photosynthesis, 
for plants without leaves, such as algae, perform it. The 
