CHAPTER XIII 
CLASSIFICATION OF PLANTS ACCORDING TO THEIR 
MODE OF NUTRITION 
1. Green plants. 
2. Non-green plants— 
(a) Saprophytes, 
(b) Parasites. 
3. Insectivorous plants. 
4. Symbiotic plants. 
1. Green Plants.—These plants are autotrophic, or self- 
nourishing. They are able, by means of the chlorophyll 
present in their green cells, to form, during sunlight, carbo- 
hydrate from carbonic acid gas. The nitrogen required 
for the synthesis of proteins is obtained, not from the air, 
but from mineral salts present in the soil. 
2. Non-Green Plants.—These, not possessing chloro- 
phyli, are unable to make carbohydrate for themselves. 
They must therefore obtain it from sources outside their 
own bodies—i.e., they are heterotrophic. Not needing 
light for photosynthesis, they generally live in darkness. 
According to the nature of the source from which they 
obtain their food, non-green plants are divided into two 
groups—Saprophytes and Parasites. 
(a) Saprophytes (Gr. sapros, rotten).—These are colour- 
less—that is, non-green—plants which obtain their carbo- 
hydrate from the rotting products of vegetable or animal 
remains. Animal excrement, since it contains organic 
material exposed to decay, is a minor source. The 
majority of fungi are saprophytes ; not being able to make 
sugar for themselves, they get it from the humus in 
which they grow. Soil-bacteria are saprophytes, and so 
are all those bacteria which initiate putrefaction or bring 
123 
