Page 3 - Lesson Notes-Morphologyof flowering plant

The roots developing from any part of the plant other than the radicle are known as
adventitious roots (L.adventitious .extraordinary). These are usually found in
monocots.
The adventitious roots can be further classified as following on the basis of nature of
development
(a) Fibrous Roots The primary root soon gets replaced by a cluster of slender, thread-
like roots originating from the base of the stem, e.g, Triticum vulgare (wheat), Oryza
sativa (rice), Allium sepa (onion).
(b) Foliar Roots These roots develop from the leaf, i.e., from the petiole of the leaf,
e.g., Pogostemon, rubber plant.
(c)True Adventitious Roots These roots develop from the nodes and internodes of
the stem, e.g., Prop roots of banyan (Ficus), climbing roots of money plant (Pothos),
roots from the stem when partially immersed in water (Coleus), roots from nodes
(Oxalis repens) etc.

Modification of Roots
The modifications are the changes in shape, form or structure in an organ to
carryout special function other than or in addition to the normal functions.
Modification of roots are found in both tap roots ancf adventitious roots.
Modification of Tap Roots
The tap roots are modified for the function like storage, nitrogen-fixation and
respiration.
(a) Conical Roots These are fleshy tap roots that resemble a cone (broad at the base
and gradually tapering towards the apex), e.g., carrot (Daucus carotd).
(b) Fusiform Roots The primary root is spindle-shaped. It is swollen in the middle and
gradually tapers at both the ends, e.g., Radish (Raphanus sativus).
(c) Napiform Roots The primary root is almost spherical (pitcher-shaped) at the base
and tapers abruptly at the lower end, e.g., – beetroot (Beta vulgaris),-turnip (Brassica
rapa), etc.
(d) Tuberous Roots The primary root becomes thick and fleshy but do not attain any
definite shape (irregularly-shaped), e.g., 4 O’clock plant (Mirabilis jalapd),
Echinocystis lobata.