We use cookies to give you the best experience possible. By continuing we’ll assume you’re on board with our cookie policy

Effect of aspect on lichen size Essay Sample

essay
The whole doc is available only for registered users OPEN DOC

Get Full Essay

Get access to this section to get all the help you need with your essay and educational goals.

Get Access

Effect of aspect on lichen size Essay Sample

In the plant kingdom lichens are unique, consisting of two totally unrelated life forms one an alga and the other a fungus, living together in a complex but balanced state of symbiosis. A symbiosis is a life form where both the partners benefit from each other. In the case of the lichen, the fungus delivers water, minerals and gases from the environment to the algae, while the algae, which contains the green pigment chlorophyll, photosynthesises to supply the fungi with sugars and carbohydrates. The algal cells are either green or blue-green, while the fungal threads or hyphae are colourless.

The fungal partner forms the body of the plant within which the algal cells are arranged, in many species, in a well defined layer 10-30m� thick just below the surface, but in others scattered between the fungal threads. The fungus also plays a role in the structure and the protection of the lichen.

The algal cells, through the process of photosynthesis provide the lichen with its organic nutrition. Lichens are photoautotrophs, so they obtain their organic nutrients using energy from sunlight.

1. The Cortex

2. The Algae Layer

3. The Pith

4. Under Cortex

5. The Rhizines

The body of a lichen is termed the thallus, and its general shape enables us to group lichens into four broad categories.

Crustose Lichens:

Crustose lichens form a crust on the surface of the substrate on which they are growing. Crustose lichens tend to grow out from their edges and have their fruiting bodies in their centre. Crustose lichens are very difficult to remove from their substrates. An example of a crustose lichen is Pertusaria Multipuncta.

Squamulose Lichens:

Some lichens have a portion of their thallus removed from the substrate to form squamules. They have an upper cortex but no lower cortex. Cladonia cenotea is an example of a squamulose lichen.

Foliose Lichens:

These have an upper and lower cortex. They are generally raised above the substrate but are connected to it by rhizines. Melanelia albertana is an example of a foliose lichen.

Fruticose Lichens:

Fruticose lichens are shrubby lichens. They are attached to their substrate by a single point, like a stem. An example of a fruticose lichen is Usnea glabrata.

The substances lichens require for nutrition is contained in rainwater and atmospheric moisture and are absorbed over the whole surface of the plant. The carbon dioxide, water and minerals held in solution and the oxygen necessary for respiration are absorbed by the fungal tissues and are passed to the algal cells in suitably modified for. The algal cells, by photosynthesis, convert these substances into the carbohydrates necessary for the nutrition of both components. Some species have blue-green cells capable of fixing nitrogen directly from the atmosphere and presenting it in a form that can be utilised by the whole lichen.

Lichens grow at a very slow rate, generally about 1cm a year for larger foliose lichens and 1mm a year for some of the crustose species. The growth rate will vary according to species, locality and season.

Before the discovery of coal-tar dyes, lichens were of considerable economic importance for the commercial dying of wool. Lichens have also been used to date substrates of unknown age. Also lichens have also been used to date archaeological remains and even to establish the frequency of earthquakes by dating rock falls.

Lichens reproduce either vegetatively, by shredding a tiny part of the parent body, or sexually by the production of microscopic fungal spores in a fruiting structure on the surface of the thallus. In many species both forms of reproduction are encountered and it is interesting that these structures are not known in other fungi.

We can write a custom essay

According to Your Specific Requirements

Order an essay

You May Also Find These Documents Helpful

Peculiarities of various assignment types

The educational process is diverse and full of interesting writing tasks which help students develop their academic abilities. Different assignments types are created by professionals in order to enhance students’ level of analytical, critical and writing skills and to vary the learning process. As a student, you will encounter numerous tasks of diverse complexities throughout your student life. Sometimes, maybe, too complicated! They have different peculiarities, structural...

Making decisions in health and social care

Critically analyses the concepts, features, and importance of costs and accounting in making decisions in health and social care Cost accounting is a method used in accounting to capture a company’s or organisation’s production costs. It assesses the input costs of every step in production, fixed costs like depreciation of capital equipment. Cost accounting measures and records costs individually then compare the input results via...

Сhildren development

Physical development 7-12 years By the age of 7 a child enjoys things such as bike riding and rollerblading they are now able to tie and untie shoelaces without adult help, they are now starting to understand what rules are and are able to follow simple rules. At 8-12 years a child improves the physical skills that they have already developed and start to see...

Forex international trading market

Introduction Forex exchange is on the rise in Namibia; resulting in more people wanting to learn how to trade to try to increase their income so that they can enhance their standard of living. Forex Foreign exchange identifies the process of converting domestic currency into international banknotes at particular exchange rates (Bofah, 2017, para.1). As the number of foreigners in Namibia is increasing, more Namibians...

Aristotelian idea of God

This image produced in 1544 shows emerging's of the Judeo-Christians and Aristotelian's traditions. Aristotle was very interested in the idea of motion and said “The world is in a constant state of motion and change”. An example of how the world is changing is the growth of trees and plants. Aristotle believed in a prime mover, which is the being which creates change in the...

Get Access To The Full Essay
icon
300+
Materials Daily
icon
100,000+ Subjects
2000+ Topics
icon
Free Plagiarism
Checker
icon
All Materials
are Cataloged Well

Sorry, but copying text is forbidden on this website. If you need this or any other sample, we can send it to you via email.

By clicking "SEND", you agree to our terms of service and privacy policy. We'll occasionally send you account related and promo emails.
Sorry, but only registered users have full access

How about getting this access
immediately?

Become a member

Your Answer Is Very Helpful For Us
Thank You A Lot!

logo

Emma Taylor

online

Hi there!
Would you like to get such a paper?
How about getting a customized one?

Can't find What you were Looking for?

Get access to our huge, continuously updated knowledge base

The next update will be in:
14 : 59 : 59
Become a Member