Plant species are able to grow in many different habitats all around the world. They can show different growth forms in different locations as they depend on a variety of environmental factors such as light, water availability, soil type, and abundance of nutrients (to name a few). Differences between plants in various environments can be due to the genetic differences between the plants or the different appearances can be due to phenotypic plasticity. Phenotypic plasticity is the ability of a genotype (genetic constitution) to alter its phenotype (outward appearance) in response to the environment. Usually a plant's genotype does not change in accordance to environmental situations but its genotype may (Biology 108 2002).

Valladares et al. (2002) observed the phenotypic responses of oak and birch seedlings to various light intensities and state that full sunlight can limit photosynthesis but deep shade can also be detrimental to plant growth and survival. Plants require very different mechanisms to cope with sun and shade so they must therefore specialize to one end of the envi

change its phenotype. The features of a plant that do not usually exhibit phenotypic plasticity are reproductive features such as flower morphology and seed and embryo development.

ronmental gradient or improve their ability to satisfy their phenotypes to the light currently presented at each particular site.

In their research, Valladares et al. (2002) found that plants grown in shade rely on enhanced light harvesting variables such as crown morphology and chlorophyll content. Also these researchers found that leaf size was larger and leaf thickness was smaller in plants that were not exposed to direct sunlight than plants that were exposed to full sunlight. These results are comparable to the results found in our experiment.

of hairs were consistent with the expected results. However because these characteristics were measured visually, they are not objective and are subject to personal interpretation, which can vary from observer to observer. Also, because they are qualitative, they cannot be analyzed statistically. The leaf surface area and thickness are quantitative data and can be analyzed statistically. Two of the null hypotheses for this experiment were that there would be no difference between the leaf surface area of the sun and shade plants and that there would be no difference between the leaf thickness of the sun and shade plants. Our data for both leaf surface area (t-test, p=0.05, df=18, t=16.0>2.101) and leaf thickness (t-test, p=0.05, df=18, t=5.7>2.101) are statistically significant, allowing us to reject the both null hypotheses and state that there is a difference between the leaf surface area of sun and shade plants and the leaf thickness of sun and shade plants. He experiment also supports the statement that Hedera exhibits phenotypic plasticity for leaf thickness and leaf area.

Some common words found in the essay are:
Sample Variance, Methods Visually, Introduction Plant, Ivy Hedera, , phenotypic plasticity, leaf thickness, shade plants, sun shade, shade leaves, leaf colour, leaf surface, sun plants, sun leaves, hedera sp, sun shade plants, leaf colour leaf, leaf surface sun, sun plant leaves, difference leaf surface,
Approximate Word count = 1367
Approximate Pages = 5 (250 words per page double spaced)