The seminar presentation discusses plant adaptations to arid environments, highlighting the significance of aridity in shaping plant survival strategies. It categorizes plants into drought-escaping, drought-evading, drought-enduring, and drought-resisting, each employing unique mechanisms such as succulence and specialized root systems. The conclusion emphasizes that despite the harsh desert conditions, indigenous plants and animals thrive due to their adaptations.

1. SEMINAR PRESENTATION
ON
PLANT ADAPTABILITY TO ARID
ENVIRONMENTS
PRESENTED
BY
SUPERVISOR: DR. (MRS.) A.A.J. MOFUNANYA
CO-ORDINATOR: DR. A.A MARKSON
DEPARTMENT OF BOTANY,
UNIVERSITY OF CALABAR
AUGUST, 2015
UKPONG BLESSING ANIEFIOK
MATRIC NO.11/091144032
Design and Implemented by Bhalodew Contact Global Limited www.balodew.com.ng

2. INTRODUCTION
 Adaptations are special features that allow a plant to
live in a particular place or habitat. These features might
make it very difficult for the plant to survive in a different
place (Braus 2005).
 Aridity is the sole factor that defines a desert and is the
primary limitation to which desert organisms must adapt
(Silverstein et al, 2008).
 Aridity is region characterized by a severe lack of
available water, to the extent of hindering or preventing
the growth and development of plant and animal life
(Helena and Billings 2011).
 Aridity results from the presence of dry, descending air.

3. FIG 1: A NATURAL DESERT PLANTS
Desert plants tend to look very different from plants native to other regions.
They are often swollen, spiny and have tiny leaves that are rarely bright green.
SOURCE: Cornell (1979).

4. STRATEGIES OF ADAPTATION
Life forms may be classified into 4 major categories that represent
strategies of adaptation, according to Solbrig and Orians, (1977).
 Drought-escaping plants: annuals which germinate and grow only
when there is sufficient moisture available to complete their life cycle.
Only their seeds persist during times of drought.
 Drought-evading plants: non-succulent perennials which restrict their
growth activity to periods when moisture is available. Typically, they are
drought-deciduous shrubs which go dormant or die back during dry
periods.
 Drought-enduring plants: evergreen shrubs. Extensive root systems
coupled with various morphological and physiological adaptations of
their aerial parts enable these hardy xerophytes to maintain growth
even in times of extreme water stress. Creosote bush (Larrea
tridentata)
 Drought-resisting plants: succulent perennials. The water stored in
their swollen leaves and stems is usually used very sparingly.

5. ADAPTIVE FEATURES OF ARID PLANTS
 Desert plants have developed three main adaptive strategies:
 Succulence: Succulent plants store water in fleshy leaves, stems or roots. Desert
rains are often light and brief, and the soil dries rapidly under an intense sun. To cope
with these conditions, nearly all succulents have extensive, shallow root systems. The
roots of a saguaro extend horizontally about as far as the plant is tall but are rarely
more than four inches (10 cm) deep. The water-absorbing roots are mostly within the
upper half inch (1.3 cm) (Dimmitt (2009). .
 Many succulents, possess a water-efficient variant of photosynthesis called
Crassulacean Acid Metabolism (CAM). CAM plants open their stomates for gas
exchange at night and store carbon dioxide. By day, while the stomates are closed,
photosynthesis is conducted using the stored carbon dioxide. Because of the lower
temperatures and higher humidity at night, CAM plants lose one-tenth as much water
per unit of carbohydrate synthesized as standard C3 plants (Delfine et al, 2001).
 Drought tolerance: Drought tolerance (or drought dormancy) refers to a plant's
ability to withstand desiccation without dying. Plants in this category often shed
leaves during dry periods and enter a deep dormancy. Most water loss is from
transpiration through leaf surfaces, so dropping leaves conserves water in the stems
Dimmitt, (1997). (Figure 1 and 2).
 Drought avoidance: Annual plants escape unfavorable conditions by not existing.
They mature in a single season, then die after channeling all of their life energy into
producing seeds instead of reserving some for continued survival.

6. b.) Just after a rain, this fern is partly
hydrated, partly dormant
a.) The vegetation here is dried out,
but still quite alive
Fig. 1 Adaptive strategies of arid plants
Source: Dimmitt, (1997).

7. ADAPTATION MECHANISM OF ARID
PLANTS
The following are the mechanism responsible for survival of
plant in desert environments:
 Seed Adaptations
 Growth Response Adaptations
 Leaves Adaptations
 Root System Adaptation
 Stem Modifications
 Leaves Adaptations: typical leaves of warm desert plants are
small and narrow (Dimmitt, 1997 )(Figure 2a), a design that
enables leaf temperature to be near ambient temperature even
when stomata are closed, so leaves can avoid lethal summertime
temperatures during summer drought (Bashan, et al, 2012).
 Root System Adaptation: the root extremely elongated, e.g. Tall
sagebrush has an extensive root system of 25meters from the plant
(Laity, 2009) (Figure 3)
 Stem Modifications: arid plants tend to alter their physical
structure. Some of this plant do not have leaves but instead depend
on chlorophyll in the outer tissue of their skin to conduct
photosynthesis (Nelson, 1976).

8. FIG 2: FEATURES OF DESERT PLANTS
Source: Phillips and Comus (2000); Laity (2009).
a.) Schott's Acacia with
very small leaves
c.) Honey Mesquite
remaining green
during a dry period
b.) Velvet mesquite
• DEEP roots (to 160 ft!) •
Microphyllous leaves

9. FIG. 3: ROOT SYSTEM CACTUS AND ACACIA TREE IN ARID ENVIRONMENT
Source: Marasco, et al, (2012)

10. CONCLUSION
The desert environment may seem hostile,
but this is purely an outsider's viewpoint
that life rarely exist in arid environment.
Adaptations enable indigenous plants and
animals not merely to survive here, but to
thrive most of the time.
This work has justify the wrong belief that
life in the desert is impossible.