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

Cardiac resynchronization therapy, This innovative, pacemaker-based approac...

This innovative, pacemaker-based approach to the treatment of patients with heart failure who have a wide QRS complex (>140 ms) on 12-lead ECG aims at providing electromechanical c

Nutrition, nutrition in paramecium

nutrition in paramecium

Ovipary, Ovipary, Vivipary and Ovovivipary In each case of external a...

Ovipary, Vivipary and Ovovivipary In each case of external and in some cases of internal fertilisation, development of the fertilized egg (zygote) occurs outside the mother's

Explain the stages of alzheimer''s disease, Explain the Stages of alzheimer...

Explain the Stages of alzheimer's disease? Stage I - There is an increased forgetfulness, anxiety and depression. Associated nutrition related changes include difficulty in

Planning and implementing nursing care - acute renal failure, Planning the ...

Planning the Nursing Care Monitor fluid intake and urinary output  Administer drugs as advised/prescribed  Monitor the child on dialysis  Provide therapeutic diet

Salts responsible for the cellular osmotic regulation, Q. What are the majo...

Q. What are the major mineral salts responsible for the cellular osmotic regulation? The main ions that act in the regulation of the osmotic pressure in tissues and cells are t

Tolerance range, what is tolerance range ? define and explain it ?

what is tolerance range ? define and explain it ?

Discuss haematoxylin and its subtypes in detail, Question 1 Discuss how yo...

Question 1 Discuss how you would perform mounting of stained sections. List commonly used mounting media in histopathology laboratory. Add a note on advantages and disadvantages o

Poisoning - pesticide toxicity, P o i s on i n g P e sticide ...

P o i s on i n g P e sticide toxicity Chemical pesticides were introduced as an important tool for pest control and have been used extensively in human health ope

Explain concept of evolutionary tree, Q. What is an evolutionary tree? Is t...

Q. What is an evolutionary tree? Is there a precise evolutionary tree known by science that explains the emergence and origin of every type of living being? Evolutionary tree i

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