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

test the hypothesis , A classic study of extrasensory perception tests the...

A classic study of extrasensory perception tests the ability of one person to read another's mind. The test uses five cards with different designs, all known to both participants.

Types of cell respiration, Q What are the kinds of cell respiration? Th...

Q What are the kinds of cell respiration? There are two types of cell respiration aerobic cell respiration a reaction with participation of molecular oxygen (O2) and anaerobic

Explain ozone shield, Explain ozone shield? Name two gases that can ca...

Explain ozone shield? Name two gases that can cause damage to this shield. Give one harmful effect of this damage each on plants and animals.

How to investigate aortic stenosis by electrocardiogram, Q. How to investig...

Q. How to investigate aortic stenosis by Electrocardiogram? Typically left ventricular hypertrophy with strain pattern is seen in severe aortic stenosis. Total QRS amplitude in

What are the functions of insulin and glucagon, What are the functions of i...

What are the functions of insulin and glucagon for the blood glucose control? Glucagon enhances glycemia and insulin reduces it. They are antagonistic pancreatic hormones. Gluc

Vibriosis/campylobacteriosis, Vibriosis/campylobacteriosis This is gen...

Vibriosis/campylobacteriosis This is genital disease of cattle and sheep. The causal organism Campylobacter fetus is a gram negative, curved or spiral shaped bacteria having s

How genes can be exchanged between chromatids, Q. How Genes can be exchange...

Q. How Genes can be exchanged between chromatids? When two homologous chromosomes physically exchangecorresponding segments during prophase I of meiosis, geneticists call it cr

Plants, In school laboratory, what is usually regarded as evidence that pho...

In school laboratory, what is usually regarded as evidence that photosynthesis has occurred in a plant

Define the obesity in children, Define the Obesity in Children? It is d...

Define the Obesity in Children? It is difficult to measure overweight or obesity in children and adolescents because they grow and mature at different rates. Weight status in c

Polyphyletic theory, Please I need short notes on polyphylrtic theory

Please I need short notes on polyphylrtic theory

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