Types of xerophytes, Biology

Assignment Help:

Types of  xerophytes

On the basis of their mbrphology, physiology and life cycle pattern, xerophytes are generally classified into the following three categories:

a) Ephemeral annuals also called drought evaders or drought escapers are common in arid zones. These annuals are able to complete their life cycle within a short period of 6-8 weeks during which moisture conditions are favourable. As the moisture gets depleted these annuals dry out leaving behind a crop of seeds to tide over the adverse dry period. They actually avoid the dry period and form seeds which are highly resistant to aridity. Argemone mexicana, Solanurn xanthouupum and Cassia tom are good examples of drought escapers.

b) Succulents: Plants adapted to hot and dry areas are called succulents. They have fleshy stem, leaves and roots which are swollen and serve as water storage organs. These plants are able to accumulate large amounts of water during the brief rainy season. To minimise water loss from the plants leaves either become very small or modify into thorns or are absent altogether to cut down water loss through transpiration. The root system is shallow, with wide horizontally spread stem and leaves are thick, swollen and leathery. Examples of succulents are Opuntia sp., Euphorbia splendens and various types of cacti, and Agave. In many cases stems become succulent as in Opuntia and Eupborbia splendens. They are also called fleshy xerophytes. In such xerophytes, cuticle is thick with a well developed two to three layered hypodermis.

c) Non-succulent perennials: These are actually the true xerophytes or drought resistants, because they possess a number of morphological, anatomical and physiological characteristics which enable them to withstand critical dry conditions. They exhibit rapid root growth and form an extensive root system to tap water from the soil in a most efficient manner. The leaf size is greatly reduced and in many xerophytic grasses, leaves roll on to reduce the leaf surface for restricting loss of water due to transpiration. Some of the examples are Calotropis procera, Acacia nelotica, Saccharurn munja In non-succulent xerophytes, root system is very extensive e.g. Calotropis.


Related Discussions:- Types of xerophytes

Define the term - microfilaments and microtubules, Define the term - microf...

Define the term - microfilaments and microtubules The cytoskeleton is, in fact, termed as the "bone and muscle" of the eukaryotic cell, and is composed of a network, consisting

Segments that form the body of the tapeworm, Q. What are the segments that ...

Q. What are the segments that form the body of the tapeworm called? What is their function? The body of the tapeworm is made of segments called as proglottids. The proglottids

Signal for ribosome to begin translating the transcript, Which of the follo...

Which of the following serves as a signal for the ribosome to begin translating the transcript? A. Addition of the poly a tail to the 3' end of the transcript B. Deamination

What is the spinal cord, What is the spinal cord? Of which elements is the ...

What is the spinal cord? Of which elements is the spinal cord constituted? The spinal cord is the dorsal neural cord of vertebrates. It is the kind of the central nervous syste

Breathing and exchanges of gases , What happens to respiratory system in a ...

What happens to respiratory system in a man going up a hill?

Deoxyribonucleic acid (dna), Deoxyribonucleic acid (DNA) is the nucleic ac...

Deoxyribonucleic acid (DNA) is the nucleic acid composed of two polynucleotide strands wound around the central axis to form a double helix; the repository of genetic information.

Closed heart surgery, CLOSED HEART SURGERY :  Operative procedures on ...

CLOSED HEART SURGERY :  Operative procedures on the heart or major intra thoracic vessels done when the heart is beating and supporting effective circulation come under the ca

What is the major constituent of the cell wall of bacteria, Q. According to...

Q. According to their morphology how bacteria are classified? Bacteria present different morphological patterns, a bacterium can be classified into bacillus, coccus, spirochete

What are the lateral lines of fishes, What are the lateral lines of fishes?...

What are the lateral lines of fishes? The lateral lines of bony fishes are sense organs that extend along both sides of the animal body. They make contact with the environment

How do taenias obtain food and make gas exchange, Q. How do taenias obtain ...

Q. How do taenias obtain food and make gas exchange? The Tapeworms have sucking and hooks structures on their heads (scolex) that fixate the parasite in the gut wall these stru

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd