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

Interrupted suture technique-prosthetic aortic valve, Interrupted suture te...

Interrupted suture technique: Synthetic braided 2 '0' sutures (ethibond) with 17mtn needles on either end and a pledget is used. Alternate green and white sutures are taken aft

Gamete formation, During the life cycle of most animals, some diploid cells...

During the life cycle of most animals, some diploid cells undergo meiosis and haploid form in a process called gametogenesis. Spermatogenesis: In the testes of the male, the

Scentific american article suggests some improvements, The human skeleton h...

The human skeleton has evolved from that of four-legged animals. Unfortunately, the adaptation is far from perfect; thus, our upright posture causes problems like backage and the k

How have prokaryotic cells give origin to aerobic eukaryotic, How have prok...

How have prokaryotic cells given origin to aerobic eukaryotic cells and to photosynthetic aerobic eukaryotic cells? As per to the most accepted hypothesis aerobic eukaryotic ce

What is the physiological explanation for the daltonism, What is the type o...

What is the type of genetic inheritance of daltonism? Is daltonism more frequent in men or in women? What is the physiological explanation for the daltonism ? The Daltonism

Tissue culture, Tissue culture The ability of a plant cell to give r...

Tissue culture The ability of a plant cell to give rise to a whole plant is called totipotency. The culture of a cell or a tissue in a suitable medium to produce new plan

Absorption of lipids, Absorption of lipids Absorption of lipids is qui...

Absorption of lipids Absorption of lipids is quite different from the absorption of monosaccharides and amino acids. Figure shows the process. The free fatty acids, monoglycer

Explain the use of trichomoniasis in pregnancy, Use of trichomoniasis in pr...

Use of trichomoniasis in pregnancy Trichomoniasis in pregnancy has been associated with adverse pregnancy outcomes (D Soper, Am J Obstet Gynecol 2004; 190:281). Metronidazole

How is the large size of some cephalopods, How is the large size of some ce...

How is the large size of some cephalopods related to the type of circulatory system they present? In cephalopods the circulatory system is closed and this gives more speed and

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