Moss stage - xerarch, Biology

Assignment Help:

Moss Stage - Xerarch

The accumulation of soil, particularly in the crevices and depressions of rock favours the growth of certain xerophytic mosses, e.g., species of Polytrichum, Tortula and Grimmia. The spores of these mosses are brought by the blowing wind. They have more or less the same power of withstanding desiccation as that of foliose lichens.

The lichens and mosses grow together and compete 'with one another. The rhizoids of mosses and foliose lichens compete for water and nutrients, and the stems of the former attain greater height than the latter. The plants in the lower strata, i.e., the lichens die, and the mosses grow. The mosses form cushion-like structure that may be a few centimetres in thickness. The substratum is thus gradually built up and is widened. The foliose lichens gradually give way to mosses that overtop the lichens. Many times, all three stages may be found on a single rock surface, the pioneers occupying the most exposed places.


Related Discussions:- Moss stage - xerarch

Duration limit of the qrs, Q. Duration limit of the QRS? The duration o...

Q. Duration limit of the QRS? The duration of the QRS is usually reduced slightly during exercise. Because catecholamines increase conduction velocity in the Purkinje fibers an

Pathophysiology of leukemia, Pathophysiology   Leukocytes develop fiom ...

Pathophysiology   Leukocytes develop fiom stem cells located in the bone marrow. During  leukocyte maturation, cells become committed  to specific cell types and develop  throu

Define the recommended dietary allowance for thiamin (rda), Define the Reco...

Define the Recommended Dietary Allowance for Thiamin (RDA)? Thiamin, as it must be clear by now, is needed mainly for the metabolism of carbohydrate, branch-chained amino aci

Protozoa., what is .groups of protozoa?

what is .groups of protozoa?

Proteins of plant origin - vegetable proteins, Proteins of Plant Origin ...

Proteins of Plant Origin Vegetable Proteins: Fresh vegetables are not considered to be a very good source of proteins. On fresh weight basis, the average protein content of s

Describe technique operation prosthetic valve endocarditis, Describe the Te...

Describe the Technique of Operation in prosthetic valve endocarditis? The operative principle is drainage of abscess, removal of debris and valve rep or replacement to reverse

Determines the concentration of cortisol in the blood plasma, If one determ...

If one determines the concentration of cortisol in the blood plasma to be 10 micrograms/mL and that in a 24 hour period a person excretes 10 mgs of cortisol, calculate the volume o

Nature of viruses, N a ture of viruses Viruses vary in their size ran...

N a ture of viruses Viruses vary in their size ranging from 20 nm (200 Ao) to 350 nm (3,500 Ao) and in shapes from spherical to bullet, rod, brick or filamentous forms. Some

Absorption of photic energy for photosynthesis, Q. What is the main molecul...

Q. What is the main molecule responsible for the absorption of photic energy for photosynthesis? And where is that molecule located in photosynthetic cells? The chlorophyll mol

Explain other lipids in biological compound, Explain Other lipids in biolog...

Explain Other lipids in biological compound? Other Lipids :  Another important type of lipids are the steroids, with a basic structure consisting of four interconnecting carb

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