The document discusses different types and modifications of plant roots. It describes the main regions and functions of typical roots, and then focuses on various root modifications that allow roots to perform specialized functions like storage, support, and absorption. Some examples of modified roots mentioned are tuberous roots for storage, prop and stilt roots for support, and aerial roots in orchids and parasitic roots in dodder for absorption.

2. What is root?
• The root is the descending portion of the plant
axis.
• As opposed to the stem, it is positively
geotropic, negatively phototropic and
positively hydrotropic.
• The root surface is non-green and it is not
divided into nodes and internodes.

3. Functions of the root
• The root performs the functions of anchorage,
absorption and conduction.
• Anchorage of the plant to the Soil is a mechanical
function while absorption of solutes and their
conduction upwards are physiological functions.
• Besides these normal functions, roots may
sometimes carry on some special functions
according to which even the structure of a root
gets modified.

4. Regions of the root
The following regions may
be distinguished in a root
from the APEX upwards.
1) Root cap
2) Region of cell division
3) Region of elongation
4) Region of maturation

5. Types of roots
Tap root system
• A root system which
develops from the radicle is
called tap root system
Adventitious root system
• The root developing from
any portion of the plant
other than the radicle is
known as adventitious root.
It may develop from the
base of the stem or from
any node or inter node of
the branch, or even from
the leaf.

6. Modification of roots
Roots may be modified to different shapes in order to
perform special functions besides their normal functions.
Root modification is found both in tap root and adventitious
root.

7. Tap root modifications
• Tap root system is modified into different
forms to carry out special function. It is
differentiated into following types:
1) Fusiform:
2) Napiform
3) Conical
4) Tuberous or tubercular
5) Pneumatophores

8. FUSIFORM:
• It is a modified tap
root. The primary
root is swollen in
the middle while
both the ends
gradually taper
forming a spindle
shaped structure.
• e.g. Radish

9. Napiform
• The hypocotyls
region is
considerably
swollen, becoming
almost spherical
and then abruptly
tapering towards
the lower end,
e.g., Turnip
(Brassica
campestris var.
rapa) and beet
(Beta vulgaris).

10. Conical
• The roots swell,
becoming
broad at the
base and
gradually taper
towards apex
forming a cone
like structure,
e.g. Carrot

11. Tuberous or
tubercular
• In this case,
the root is
thick and
fleshy but
does not form
any definite
shape, e.g.,
Mirabilis
jalapa.

12. Pneumatophores
• These roots grow
vertically up and come
out of the water or
marshy soil like conical
spikes. They occur in
large numbers around
the tree trunk. Such
roots are provided with
numerous pores
(breathing pores)
through which air is
taken for respiration,
e.g., Rhizophora.

13. B. Adventitious root modification
• Roots produced from any portion of the plant
other than the radicle is called adventitious
roots. It may be changed to different forms for
special functions such as storage, mechanical
support and vital functions.
(a) For storage of food:
(b) For mechanical support:
(c) For vital functions:

14. For storage of food
In this case, adventitious
roots grow from the
nodes of the running
stem. These roots swell
and get modified to
irregular forms, known as
tuberous. These are
produced singly,
e.g., Sweet potato
(Ipomoea batatas).
Tuberous root

15. Fasciculate
root
• In Dahlia,
Asparagus the
tuberous roots
are developed
from base of
the stem! in
clusters.

16. Nodulated
root
• Plants belonging to
laguminosa family
develops nodules.
These are produced
by nitrogen fixing
bacteria and they
get carbohydrates
from plants
• This swelling
developed by roots
is known as
nodulated root
• E.g. plants of
laguminosae family

17. Moniliform or
Beaded root:
• Swellings are
found in the root
at frequent
intervals. It gives
rise to a beaded
or moniliform
appearance
• e.g.Momordica,
Vitis , Dioscorea
and many grasses.

18. Annulated
roots
• In this type, the
root has a
series of ring-
like swellings
appearing as if
formed by
number of discs
placed one
above another,
e.g., Cephalis
ipecacuanha.

19. For Mechanical Functions
• These roots are
developed from the
horizontal branches of
some trees in vertically
downward direction. On
reaching the soil each
root grows into thick
and woody pillar-like
structure which gives
support to the branch
from where it
developed.
• These are found in
Indian rubber and
banyan.
Prop Roots

20. These are stout roots
developed obliquely from
the lower part of the
trunk; grows on soft soil.
On reaching the soil they
help the mother plant to
keep erect and also give
an additional anchorage
support to prevent from
being uprooted.
These are found in screw
pine, maize, sugarcane
etc.
Stilt root
Stilt Roots

21. Root-Buttresses
• These are plank-
like structures
developed with
the contribution
of both stem and
root, come out as
erect projections
from the basal
region of the
trunk.
• Eg. Bitter almond

22. Climbing Roots
• These are the roots
developed from the
node of some weak
plants and help to
climb the host plant.
The apices of these
roots produce a
viscous substance
which is dried in the
air and so the roots
get themselves
attached to the host
plant. These are
found in betel vine
(Piper betel)

23. Clinging Roots
• These are the short roots
which, after developing
from the stem, penetrate
into the cracks and
crevices of the supporting
trees and help to fix the
plant with the host plant.
In addition to anchorage,
they also absorb some
food from the
accumulating debris on
the host plant.
• These are found in Vanda

24. For vital functions
For Absorbing Moisture from Air
Epiphytic Roots
• These are hanging aerial
roots of epiphytic plants.
The roots are covered by
a thin greyish layer (4 -5
cell-layer in thickness)
known as velamen. The
velamen can absorb
moisture from the
atmosphere. It is found
in orchid root (Vanda)

25. Parasitic Roots
• These are also called
sucking roots or
haustoria. The small
root like structure,
after developing
from the stem of the
parasite, penetrates
the tissue of the host
plant and absorbs
food.
• These roots are
found in dodder

26. Assimilatory or
Photosynthetic Roots
• Roots of some
plants develop
chlorophyll and
become green.
These roots are
able to prepare
carbohydrate foods
through
photosynthesis.
• E.g.Tinospora
cordifolia (Galo)