Transcript Exam Objective

Exam Objective
• Describe with the aid of diagrams and
photographs, how the leaves of some
xerophytes are adapted to reduce water loss
by transpiration
Xerophytes
• These live in
 Hot, dry desert regions
 Cold regions where soil water is
frozen for most of the year
 Exposed, windy locations
Introduction
• Xerophytes are plants that have
adaptations to reduce water loss by
transpiration
Examples of
xerophytes
Sections through
xerophyte leaves
Cactus
• Has spines instead of leaves, to reduce water loss
• The stem (cactus pad) is green and contains
chlorophyll, acting as leaves do in other plants
Taken from Xerophyte Question in OCR Green Book on Moodle
Xerophytes – some key ideas
xerophytes = plants living where water is in short supply
transpiration reduced
thick, waxy cuticle
stem stores water
small leaf surface area
rolled leaf
absence of leaves
extensive roots
water potential gradient
sunken stomata
stomata open at night / close in day
stomata surrounded by hairs