This document discusses the adaptations of xerophytic plants to survive in environments with little water availability. It describes their root, stem, leaf and physiological adaptations. Roots have root hairs and thick cork layers to protect tissues. Stems have thick cuticles and hypodermal layers. Leaves are succulent with water storage tissues or have thick cuticles, sunken stomata and compact mesophyll tissues. Physiological adaptations include regulation of stomatal opening and closing, accumulation of compounds in cell walls, and high osmotic pressure of cell sap to reduce water loss through transpiration.

1. Dr. B. KARUNAI SELVI
ASSISTANT PROFESSOR OF BOTANY
V.V.VANNIAPERUMAL COLLEGE FOR WOMEN
VIRUDHUNAGAR- 626 001
TAMIL NADU, INDIA
karunaiselvi@vvvcollege.org
Xerophytes

2. Xerophytes are plants which able to survive in
an environment with little availability of water
XEROPHYTES- ADAPTATIONS

3. Root
 Roots posses a number of root hairs and well
developed root caps.
 Roots are covered with thick cork-like layer. It
protects the inner tissues. eg. Pinus edulivs,
Calotropis storage tissues.
 They have well developed stelar system.
 Intercellular spaces are very much reduced.
 Mechanical tissues are well developed and
made of thick walled cells.

4. Stem
 In succulent xerophytes stem posses a water
storage region.
 In Non-succulents
 Cuticle is very thick.
 Epidermis is well developed, with thick and cell
walls.
 Hypodermis is several layered and
sclerenchymatous.
 Stomata are sunkun type.
 Vascular tissues are very well developed,
differentiated tissues are very well developed.
 Bark is very well developed.

5. Leaves - Succulent
 Epidermal cells of
leaves serve as
water-storage organs.
Eg : Peperomia.
 They have prominent
water storage regions
in their mesophyll. Eg:
Aloe.
 Cuticle is thick-heavily
deposited with cutin
and cellulose.
Aloe vera

6. Leaves - Non - succulent
 Well developed heavy
cuticle.
 Several layered
epidermis. Eg:
Nerium.
 Several layered
sclerenchymatous
hypodermis in Pinus.
 Mesophyll very well
differentiated in to
palisade and spongy
parenchyma.
C.S. Of Nerium Leaf
Under compound Microscope

7. C.S. of Nerium Leaf
Diagramatic
representation
of cross section
of Nerium leaf
By
Ms.V
Jeyalakshmi
III B.Sc.
Zoology, VVV
College,
Virudhunagar

8.  Stomata of sunken
type confined only to
lower epidermis.
Eg:Nerium.
 Vascular tissues are
very well developed
differentiated in to
xylem with lignified
elements and phloem.
 In Pinus, well
developed complex
transfusion tissues
are present.
C.S. of Pinus Needle

9. C.S. of Aloe vera Leaf
Diagramatic
representation of
cross section of
Aloe vera leaf
By
Ms. V.
Jeyalakshmi , III
B.Sc. Zoology,
VVV College,
Virudhunagar

10. Rolling of leaves
 Grooves are seen on
the adaxial surface.
 Stomata are seen
only in the grooves.
 Vascular bundles are
present in the ridges.
 Mesophyll cells are
sclerenchymataus.
 Photosynthetic
tissues are present at
the grooves.
Rolled leaf

11. Physiological adaptation - Stomata
 In dark plants respire
and produce acids.
 Acids in the guard cells
increases osmotic
concentration.
 This cause inward flow
of water in the guard
cells.
 guard cells turgid, the
stomata open.
 In light acids dissociate
to produce Co2.
 Co2 used up in the
photosynthesis.
 Osmotic concentration of
cell sap decreases.
 This cause closure of
stomata.
Stomatal opening Stomatal Closing

12. Physiological adaptation of
xerophytes
The chemical compounds of cell sap are connected in to
wall forming compounds
 They are finally incorporated in to cells walls.
 Polysaccharides converted in to cellulose, formation of
suberin.
Catalases, peroxidases are more active:
 Amylase enzyme hydrolyses the starch very actively.
Drought resistant capacity due to
 Structural features.
 Resistance of hardened protoplasm to heat and
desiccation.

13. Regulation of transpiration
Transpiration regulated by
 Cuticle
 Polished surface
 Compact cell
 Sunken stomata
 Stomatal hairs
 High osmotic pressure of cell sap:
 High osmotic pressure increases the turgidity.
 High osmotic pressure affects the observation of
water.

14. References
 http://cdn.biologydiscussion.com/wp-
content/uploads/2016/05/clip_image026-22.jpg