Weed study. Dandelions - descrption and characteristics. Investigation to dandelion distribution.

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Introduction

One of the most familiar wild plants is the dandelion.  It is, however, a troublesome plant that is a weed in lawns and gardens.  

The dandelion lives throughout the temperate zones. It is a perennial, surviving winter and re-growing in early spring. It blooms in spring and summer.

The roots may be up to five feet (1.5 meters) deep. The deeply lobed leaves grow out from center close to the ground. The best way to get rid of dandelions in a lawn is to use a weed killer.  They also may be pulled, but it is necessary to loosen the plant so that the entire root comes out.

Dandelions belong to the composite family of plants. The blossom is actually a bouquet of about 150 to 200 tiny flowers set in a solid head on a receptacle.

Each flower is a perfect seed-producing floret. As the small, dry, one-seeded fruits mature, they push up a feathery structure called a pappus on a threadlike stalk. All the pappi together make up the blow ball.

The wind takes the seeds and scatters them far and wide.

Dandelion greens are a delicacy in the spring when the leaves are tender and fresh. They can be boiled or eaten raw in salads. The word dandelion comes from the French dent de lion, meaning 's tooth. The scientific name is Taraxacum officinale. 

Picture number one shows a fully blossomed dandelion, these are most likely to be seen in early spring.

Picture number two represents a picture of a group of dandelions.  This picture is more precise as you can see the green leaves.  They are easy to identify, as they resemble the holly leaf.

To the suburban homeowner this deep-rooted wildflower may be nothing more than a pest, an unsightly blight in the lawn. Yet nutritionists prize dandelion greens as a rich source of vitamins A and C, and in fact this brings $300,000 to $400,000 annually to the farmers of southern New Jersey, who supply dandelion greens to produce markets throughout the country.  

Dandelions increasingly irritate gardeners, as it is difficult to eradicate them totally.  Therefore I will also research about ‘WEEDS’.  Researching their desired habitats.

Weed

According to the common definition, a weed is any plant growing where it is not wanted. Any tree, vine, shrub, or herb may qualify as a weed, depending on the situation; generally, however, the term is reserved for those plants whose vigorous, invasive habits of growth pose a serious threat to desirable, cultivated plants.  A dandelion is often regarded as a weed.

Through competition for light, moisture, minerals, and soil, a weed robs cultivated plants of vital resources.  Weeds pose other threats as well. Halogeton (Halogeton glomeratus), a weed accidentally introduced into the Western states some 50 years ago, is highly toxic to sheep.  

A significant factor in the success of the common weeds is their fertility. By blanketing an area with seed, they overwhelm less vigorous plants. One plant of pigweed, a common annual weed, may produce 117,400 seeds in a single year. As many as 1,147 seeds per square foot (12,342 seeds per square meter) may survive in the top inch of topsoil alone. Such seeds can retain their vitality for a remarkable length of time. In 1879, for example, botanist William Beal buried a pint bottle containing 1,000 seeds of 20 common weeds. Unearthed in 1980 the 101-year-old seeds still yielded a small but vigorous harvest of 26 seedlings.  The dandelion has the ability to grow their roots up to 5 feet under the ground.  They also spread their seeds to reproduce by the force of the wind.

A variety of ingenious adaptations assist weeds in dispersing their seeds, providing them with other advantages over less aggressive species.

The seed capsules of the cocklebur (Xanthium pensylvanicum) use hooked prickles to attach themselves to the fur of passing animals and ride to new territory, while the seeds of the common plantain have a coating that turns sticky when moistened by a shower or heavy dew, enabling them to hitchhike on the shoes of unwitting pedestrians.

As important to the success of weeds as their fertility is their adaptability. Weeds flourish in conditions that would kill less hardy plants. Cultivated tomatoes are very sensitive to saline soil, yielding poorly if as few as 2,500 parts per million of salt are present in the soil.

Such adaptability also makes weeds important members of the class of plants botanists call pioneers. These are the species that first colonize disturbed habitats, lands stripped bare by natural catastrophes or by human exploitation. The colorful perennial known as fireweed (Epilobium angustifolium), for example, earned its name for the speed with which it follows in the wake of forest fires.

Equipped with parachutes of fine hairs, the fireweed's seeds float on the breeze to sow themselves throughout burned-over lands. Thriving on the nitrates they find in the ashes, the fireweeds assist the process of reforestation by stabilizing the soil, thus halting erosion.

Weeds, in fact, may benefit the environment in a number of ways. They help to invigorate poor or exhausted soils, adding humus as they decompose.

By sheltering the soil from the sun and wind, weeds actually promote the germination of other, less rugged plants. Birds, rodents, and many other kinds of wildlife depend on weeds for the berries and seeds they furnish. Animals also find shelter in the cover provided by the weeds' foliage.

A promising area for future investigation is allelopathy, the phenomenon by which certain plants themselves control weeds by releasing toxins into the soil. Sorghum, sunflowers, and some strains of cucumbers have demonstrated an ability to curb weeds in croplands. Among the most effective allelopaths are the common weeds quack grass and Johnsongrass. This fact has led some scientists to theorize that the weeds of today may be the weed killers of tomorrow.

These pictures are just some of the many weeds that exist.

  • Picture 1: is a picture of the ‘Queen’s Anne’s Lace’, or commonly known as wild carrot.
  • Picture 2: is a picture of the poison ivy.

Interactions between plants affect their distribution and abundance. When a major resource, such as water or nitrogen, is in short supply, plants may compete with each other for use of the resource. Species that can use the resource more effectively are likely to grow faster and therefore to be more abundant.

Such competition affects plant succession. Competition is also apparent in such ecosystems as agricultural fields.

Many weeds are better able to use water and minerals than are the crop plants with which they grow. Consequently, farmers must employ various methods of weed control in order to check the spread of weeds.

Changes in the community during secondary succession are rapid, because every living thing contributes to its alteration. For instance, the weeds that grow on a vacant lot produce shade and increase the soil's ability to absorb and store water. They also attract insects and birds and enrich the soil when they die and decay.

The bare ground of the vacant lot is the best possible place for the pioneer sun-loving weeds to grow. Later tree seedlings replace the weeds if the lot is in a forest climate, by native grasses if it is in a grasslands climate. Such changes occur until plants and animals that can make maximum use of the soil and climate are established.

Dandelions, milkweeds, cattails, thistles, and asters have seeds with fluffy little parachutes. They drift through the air on the slightest breeze if the air is dry. On damp days, when the seed would not be able to travel far, the parachute stays closed. Seeds may travel many miles on their parachutes.

For this assessment I will have to investigate the Dandelion within a grassland area.  I have decided to conduct this investigation due to the dandelions strong nature.  Many botanists have researched the existence of the Dandelion and have made many theories on its living in nature.  Gardeners and botanists have diverse opinions on the Dandelion.  Some classifying it as a ‘weed’ and some consider it a benefit to their garden.  However, the Dandelion is a very strong planate, and it would be interesting to see how abundant they are within these two areas.

I will investigate my project within two different the grassland area and the chalk land area.  I have decided to use two different sites and make scientific comparisons. Due to the dandelions nature of being strong and sturdy. I have assumed that more will be present within the grassland area.  (This maybe a part of my prediction).  The grassland area is situated at Juniper Hall Field Centre, in Dorking in Surrey.  My investigation will be investigated at this site.  Our previous visit to this centre was very successful as we acquired much knowledge on that intense course.  I can extract and use information which I attained from that specific AS course.  My coursework title was ‘the abundance of large creeping mosses’.

To attain accurate and efficient results I will have to carry out an experiment, where I have to plan.  I decided on how to implement my experiment.  (I will justify in my method, which steps I took).  There are many methods, which I can use to implement my investigation.  Last year I used Random sampling to investigate the abundance of ‘Large Creeping Moss’, within a 40 square metre area; using gridded quadrates for accuracy.  My techniques had improved a vast amount; hence have decided to adopt the same procedure for my A2 course, with minor adaptations, these will be explained and justified in my method.

I will try and repeat my investigation as many times as possible to attain accurate and efficient results.  I have a vague idea of the method that I will use.  This will be explained later on.  I may include the results that I used last year to show how I presented my results.  

There are many risks and safety precautions in which I took.  I had to make sure that I dress up appropriately according to the weather.  It was not raining heavily, however it was very cold.  Therefore, making sure that I dressed up warm is vital, as there is huge risk of catching hypothermia.  I will also make sure that I wear gloves protecting my hands from catching diseases.  There are many diseases linked to unhygienic substances related to animals.  Wearing gloves will not only affect my health, but also distort my results; our skins pH level is 5.5.  Therefore if I perspire I may affect the results of the soil pH.

There are many factors, which may distort my results.  For example, whether or not the pH levels effect the dandelions, or if the soil depth effects the stability of the dandelion.  Many questions will arise during the course of my investigation.  It is therefore my duty to assign as many as I can. I may not be able to respond to each one due to the time factor.  I may decide to include more factors to my investigation, and therefore apply them to my investigation, regarding I have the time.  

I have, attained a vast amount of knowledge, from the biology course I am studying; hence I will apply it to my investigation.  For example I will discuss the population size of dandelions, competition and adaptation of the dandelion.  Also, the dandelion may be a vital food supply for a certain organism, which will affect the amount of dandelions, which are present.  The season, as I implemented my investigation in September, the light intensity has decreased, which may have effected how the dandelion photosynthesis.  All these factors will be considered when I write my conclusion.  

My background knowledge will also help me in my investigation.  From the research that I have attained, I have acquired a sufficient amount of knowledge to address any inaccurate results.  I feel that this investigation has not only been a part of an assessment, it has given me the chance to broaden my horizons in Ecology, and Zoology.


Aim

My aim from my A/S biology coursework was very similar to my experiment, which I have decided to implement for my A2 level coursework.  However, the aim of this investigation was in depth, with justified scientific knowledge.  I feel that I did not conduct my experiment to my fullest potential during my A/S course, however I have recognised this.  Therefore I will implement my experiment making sure that I have covered everything that I did not include in my A/S level coursework.  

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The aim was to actually to investigate the abundance of Dandelions (Taraxacum officinale.), in two different sites.  The lawns, which I used, were present at Juniper Hall Centre, established in Dorking, Surrey.  The lawns, which I used to implement my experiment, are called Templeton Lawn (see Appendix), and Lower Lawn (see Appendix).  These are two trampled areas, which are used for recreational activities.  

Templeton lawn has a large tree (see appendix), which provides shade to the species on the lawn, whereas the Lower lawn does not.  You can also predict the appearance of the lawns, however this ...

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