The document discusses the structure and organization of plant roots. It describes three main root system types: taproots, fibrous roots, and adventitious roots. It then details the internal structure of individual roots, including the root cap, root apical meristem, region of elongation, and region of differentiation. Key cell layers like the endodermis and the Casparian strip that runs within it are also summarized, with the strip acting as a selective barrier between root tissues.

1. ROOT
ANATOMY

2. EXTERNAL STRUCTURE
Organization Of Root Structure
Structure Of Individual Roots

3. ORGANIZATION OF ROOT SYSTEM
Taproot – develops and forms
the embryonic root called the
radicle, that was present in the
seed; after germination, it
grows extensively and usually
become the largest root in
the system.

4.  Fibrous roots - the opposite of a taproot
system. It is usually formed by thin,
moderately branching
roots growing from the stem.
 A fibrous root system is universal in
monocotyledonous plants and ferns.
 The fibrous root systems look like a mat
made out of roots when the tree has
reached full maturity.

5.  Adventitious roots - roots are plant roots
that form from any non-root tissue and are
produced both during normal development.

7. STRUCTURE OF INDIVIDUAL ROOTS

8. INTERNAL STRUCTURE
 Root Cap
 Root Apical Meristem
 Region of Elongation
 Region of Differentiation
or Maturation

9. ROOT CAP


10. ROOT CAP
Thimble-shaped mass of parenchyma cells at the tip of each
root protects the root from mechanical injury.
 Dictyosomes or Golgi bodies release a mucilaginous
lubricant (mucigel) cells that lasts less than a week, then
these die possibly important in the perception of gravity (i.e.,
geotropism or gravitropism) amyloplasts (also called
statoliths) appear to accumulate at the bottom of cells.

11. ROOT APICAL MERISTEM
 Apical meristem - cells divide
once or twice per day.
 The transitional meristems
arise from the tips of roots and
shoots.
These include:
– the protoderm
(which forms the epidermis)
– the ground meristem
(which forms the ground tissue)
– the procambium
(forms the primary phloem
and xylem)
- quiescent center
(reserve meristem)

12. Region of Elongation
It is the region where cells
expand greatly; some
meristematic activity
continues, out mostly cells
are enlarging.
 In this region, tissues are all
permeable.

13. Region of Maturation or Differentiation
Root hairs develop as
protuberances from
epidermal cells.
 Increase the surface
area for the absorption
of water.

14. ENDODERMIS
 Is the central, innermost layer
of the cortex in land plants.
 It is a cylinder of compact living cells,
the radial walls of which are
impregnated with hydrophobic
substances to restrict the
apoplastic flow of water to the inside.
 The boundary between the
cortex and the stele.

15. CASPARIAN STRIP
 A band of waterproof, corky
tissue that is found on the side
and walls of the endodermis
of roots.
 The strip prevents water from
entering the pericycle except
through the cytoplasm of
endodermal cells; this may
be important in producing
root pressure.

16. The Casparian strip is a waxy-like material or substance that
layers around the endodermis.
 Due to its hydrophobicity, water or dissolved minerals in the
water will be prevented from moving from the cortex into the
vascular cylinder and vice versa.
It will prevent anything from moving between the cells. So if any
material wants to move from the cortex to the vascular cylinder,
they now have to first move into a cell, then will be transported
cell to cell through connections between cells.
The purpose of this action or mechanism is to filter out which
materials are needed to be transported into the vascular cylinder
from those materials that are unnecessary or harmful to the
plant.

17. DICOT ROOT

19. MONOCOT