root , types, forms, examples

1. Root
morphology

2. Root
The plant organ that is devoid of
a) Chlorophyll
b) Buds
c) Leaves
• It shows positive gravitropism and moves
away from the light
• Root cap is present at the tip
• Fines, delicate root hairs are present for
the water absorption

3. Kinds of roots
Tap root:
the first root that is formed by the
elongation of the radicle of the embryo in
the seed is called tap root
Adventitious root
Roots which arose from the stem , leaves ,
other then radicle part is called adventitious
root

4. Forms of tap root

5. Fibrous tap root
In herbaceous annual plants , such as bean
and pea,
Tap root elongates and gives off branches
Long and slender tap root is called fibrous
Nodulated roots : In medicago the tap root
bears small swellings of nodules ( these
bacteria fix nitrogen and forms nitrates)
These bacteria provide nitrates to plants and
And In return gets protection and shelter
from roots

7. Tuberous tap root
When the tap roots are thick
and store reserve food , they
are called as tuberous roots.
Occurs in biennial plants
examples: carrot, radish ,
turnip and beet, oak , dandelion

8. Biennial plants
These plants live for two seasons
 In the first season they produce leaves
only and store up the surplus food in the
tap root
 In the nest season, they use that stored
food for flower production , after they
die.
• Conical tap root: it is swollen form the
top and tapering from the ends e.g.
English radish and English carrot.
• Napiform tap root : this type of root is
very much swollen form the tap and
abruptly tapers from the lower side. E.g.
turnip and beet

9. Adventitious roots

10. Various forms of adventitious
roots are present.
 Subterranean or underground adventitious
roots
 Partly subterranean adventitious roots
 Aerial roots
 Parasitic roots
 Aquatic roots

11. 1: Subterranean or
underground Adventitious roots
They arose from the part of stem , which is in
contact with soil . They may be of fibrous or
adventitious type
1: fibrous adventitious root:
They are long and slender commonly
creeping on underground stem. E.g. grasses ,
ginger
2: tuberous adventitious root:
They are swollen and fleshy, containing
stored food. They are present in Dahlia,
sweet potato and many orchids .
In dahlia and sweet potato some roots remain
fibrous, while others enlarge greatly to form
tubers

12. 2: partly subterranean
adventitious roots
They are present partly above or partly
below the ground . They may be classified
into
• Stilt roots
• Prop roots
• Aerating roots

13. a) Stilt roots
 When the roots arise from the lower
portion of the stem and grow obliquely
down into the soil where they develop in
the normal manner
 They are called stilt roots
 They fix the plant firmly in soil and keep
it erect
 Examples : maize , sugar cane, bamboo ,
palms

15. b) Prop roots
These roots grow vertically downward in the
air from which they absorb moisture
On reaching the soil they absorb water and
minerals from it
After this they behave as stouter and form
props and pillars which support the branches
.
Banyan tree ( Ficus bengalensis)
Rubber tree ( Ficus elastic )

16. c) Pneumatophore roots/
aerating roots
Such roots are found in plant growing in
mangroves or swamps near the sea-shore.
Pneumatophores arise vertically upwards
and come out of soil and water. They bear
small pores called pneumatophores or
lenticels for exchange of gases, e.g.
Heritiera.

17. 3 : Aerial roots
They are exposed to air and carry specific
functions . They are of to types
• Clinging or climbing roots
• Absorbing roots

18. a) Clinging or climbing roots
They are developed from stem,
They are sensitive to touch and support
They secrete a fluid and when they are
exposed to air, that dries up , helps plant to
support
Sometimes they form disc like structure , to
ensure the firm attachment with the host
Ivy ( Hedera helix)
Long pepper ( Pipper longum)

19. b) Absorbing roots
These are present in epiphytes , in tropical
rain forest
They have long adventitious roots which hang
freely in air and absorb moisture from air
These roots are covered by dead , spongy
tissue called as velamen. That absorbs and
store water

20. 4: parasitic roots
In parasitic flowering plants, various roots
arise from the stem of the plant where it is
near to its host .
They are also called as haustoria
They penetrate into the stem and become
connected with its conducting tissue
They absorb the manufactured food from the
host and pass it to the stem of parasitic plant
Cuscutta

21. 5: aquatic roots
In many water plants , clusters of fibrous
adventitious roots arise from the stem and
dangle ( swing) in water .
They are usually without root hairs

22. Functions of roots
 Anchoring
 Absorbing
 Storage
 Clinging , propping and absorption
as haustoria
 Involved in vegetative
reproduction ( Dahlia plant , it
stores excess food and serves as
source in next season)
 Develop buds and grow into new
plants