BOTANY Higher Secondary Second Year - Textbooks Online

Certain angiosperms like Monotropa lack chlorophyll and have mycorrhizal
roots. This plant absorbs nourishments from the humus through their
mycorrhizal roots.
Parasitic plants
Some plants get their nourishments from other living plants or
animals. They are called parasitic plants. The plants or animals from
which the parasites get their nourishments are called hosts. Parasites have
some special roots, which penetrate the host plants and absorb food from
the phloem and water and minerals from xylem. These roots are called
haustoria.
Parasitic angiosperms are of two types. They are total parasites and
partial parasites. Some plants completely lack chlorophyll and do not
grow in the soil. Therefore, it is totally dependent on the host stem for
organic food materials, water and minerals. They are called total parasites.
eg. Cuscuta. Cuscuta has thin, pale yellow and leafless stem. It twines
around the stem of the host and sends haustoria into it to absorb
nourishments.
Some plants absorb only water and mineral salts from the stem of
host plant. They can manufacture their own food due to the presence of
green leaves. The haustoria of these plants have connection only with the
xylem of the host to absorb water and mineral salts. These plants are
called partial parasites. eg. Viscum.
Insectivorous plants
Though insectivorous plants are capable of manufacturing carbohydrates
by photosynthesis, they are not able to synthesize enough proteins due to
the deficiency of nitrogen. They overcome this deficiency by catching
small insects and digesting them. Their leaves are modified in various
ways for this purpose. Such plants are called insectivorous plants.
Eg. Drosera.
Drosera
Drosera is a small plant growing in marshy places. This plant is also
known as sundew plant. The leaves of this plant have numerous hair-like
structures called tentacles. Each tentacle has got a gland at the tip. The
gland secretes a sticky fluid. This fluid shines in sunlight and appears as
dew; hence the plant is called sundew plant.
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