Abstract
Plants are adapted to the different ecological regions through the exhibition of various unique features. Plants’ adaptations to the various habitats categories have been widely studied about the diverse ecological conditions. The study of the adaptation of plants into those areas where they have been examined through the study of the plant organs such as roots, stems, leaves among others. The study of the morphological and anatomical characteristics of the various organs is very important for the biological study of the plant’s functioning and processes.
Leaf morphological and anatomical variations of plant species in a given habitat have been of great interest in the investigation to establish their relations to ecological conditions. However, there is little research that has been carried out on the leaf variations at the intra-tree level. Extensive work has been done on different plants species in different habitats. This paper thus explores the leaf morphological and anatomical features at the intra-level in effect to the ecological condition specifically to light factor. Quercus rubra (red oak) is being used in the study. The data collected in the study are tabulated analyzed using descriptive data methods such as mean or average. Finally, the results were discussed and a conclusion was drawn thereafter.
Introduction
Morphology and plant productivity
Plants have several organs which play fundamental roles in plant life. These include roots, stems, and leaves. The various organs are interconnected in their roles in one way or another to carry out their functions effectively; however, leaves are the most significant for the plant photosynthetic process, where the light factor has great effects. Generally, the morphological organization of the plant’s organs has been an area of numerous paradoxes, and in most cases, the structure of the various organs has been portrayed as a mosaic of contradictory regarding plant requirements and productivity. Plants require light for photosynthesis. The photosynthetic rate depends on the input and the output of the materials needed to carry out the process. This means a large leaf surface area is necessary for capturing the light energy, but a large surface area induces high water loss from the plant body. Plants adapt to this dualistic purpose through the integration of different morphological and anatomical features that keep the process at the optimal point, through the channeling of the necessary elements for photosynthesis into the plant body, and elimination of the excess ones such as water and CO2. This complex control perhaps compromises the plant life productivity (Martin, 3).
Leaf Morphology and ecological conditions
Plants in their macro-environments exhibit certain adaptations of the various organs. These adaptations include both morphological and anatomical features which help the plants to better survive in the environments they grow. Different plants exhibit leaf variations ranging from leaf size, leaf shape, as well as the number of internal contents such as the number of chloroplasts and cell layers. In addition, plants also may show different leave arrangements depending on the ecological conditions in which the plant grows. Some of the leaves are thickened while others are thin; these disparities perhaps are brought about by biological factors like genetic compositions or environmental factors which include temperature, light, soil among others. Biological factors are generally less varied for single plant species, hence inner structures of their organs assume similar morphological features such as microphylls and chloroplasts (Mantovani 2).
Leaf morphology variations and their functions
Maximum light absorption is very significant for the high photosynthetic productivity of the plants. Maximum light absorption in a plant may be achieved in several ways. This is evident for plants growing in different ecological conditions. Additionally, leaf variations have been revealed to exist for different taxa, and there is also some evidence that leaf variations occur within a plant in response to local changes in the environment. Different plant species thus show considerable leaf variations on shape, weight, and surface area in response to environmental conditions such as temperature and light (Coker and Kent 1).
Materials and method
Materials
The following materials were used in this experiment: 50 sun oak leaves and 50, shade oak leaves, graph paper, pencil, top-loading balance, ruler and thread string,
Methodology
50 sun leaves and 50 shade leaves were placed labeled on the benchmark ready for different analyses. Each of the leaves was analyzed to establish its characteristics. A thread string was stretched lengthwise from one end of the leaf through the center to the other end and then tracing the thread string on the ruler to establish the leaf length. Similarly, the thread was traced across the leaf and then the measurements were taken by tracing it on the ruler. Afterward, the thread was wound around the leaf, and then tracing the length of the wound thread was on the ruler to get the perimeter of the leaf. The area of each leaf was determined by careful tracing its shape on square graphical paper and using the least square method calculating the surface area of the leaf as well as the leaf sinus area. Finally, each of the leaves was placed on a top-loading balance and the reading was taken for each leaf and recorded. The data was tabulated as shown in table 3 and analyzed using descriptive data analysis.
Results
Surface area
The data of the two leaf categories had a property of precision with just very few leaves whose values were greatly varied from the others. The leave that was drawn from the exterior parts of the plant had an average surface area of 72.5, while that of the leaves that were labeled as shade leave had a mean surface area of 81. 5cm2. The average surface area for the sun leaves was considerably less as compared to that of the shade leaves. Hence, the overall means surface areas of the sun and shade leaves were between the extremes. Certainly, the mean surface area of the shade leaves was skewed to the right side of the overall mean of the combined surface areas for sun and shade leaves, while the mean surface area of the sun leaves was to the left side of the overall mean area.
Leave on the exterior part of the plant can receive adequate light from the sun as the light is not obscured by other leave as compared to those in the lower interior shaded regions. Hence, for the plants to maximize the light falling on their leave, those on the exterior regions have reduced surface area to permit light to penetrate the interior parts. Those leaves on the lower shaded regions have a larger surface area so that the little light which penetrates through the exterior leaves surfaces are captured by the leaves at the lower shaded parts.
Weight
Moreover, the leaves from the different plant microenvironments indicated a variation in their weights. Similar to the average surface areas, the shade leaves had more weight than the sun leaves. The average weight of the sun leaves was indicated as 1. 2g while that of the shade leaves was higher by 0.3, hence showing an average weight of 1.5g. The average weights of the leaves from the two classes were thus not widely varied as it was with the average surface areas.
Despite the fact, the sun leaves and shade leaves had different mean averages of area and weight; they had one thing in common concerning the distribution of their perimeters. On the extremes side of the perimeter of 0.5cm and 2.5cm, there were very few leaves at these extremes. However, most of the leaves’ perimeter fell in the range of 60. cm and 90. cm with very few of them measuring above this and below 48. cm. Most of the sun leaves were clustered on the weight range of 1 and 1.5g. On the other hand, the shade leaves were clustered between 1.5g to 2. g, but they were widely spread from one another about their perimeters. A large proportion of the shade leaves had a maximum perimeter of about 80.cm but very few of them fell above 80. cm. The results also showed that some of the leaves had a perimeter of below 40. cm. Generally, shade leaves were clustered between 45. cm and 70. cm
Discussion
The results for the sun and shade leaves study indicated that they had several parameters that varied greatly from each group. The mean area of each of the two groups was estimated as a product of the length and width of the leaves in the group. The mean area difference of the two group categories indicates the leaves also differed in length and widths. Moreover, the difference in weight showed that the internal anatomy of the shaded and sun leaves differed with leaves at the shaded regions having a greater number of chloroplasts. Generally, variations on a single factor in the morphology of the leaves gave rise to the overall dissimilarities of the two groups.
Conclusion
The study of plant morphology is important in the establishment of the various factors’ interrelations to the ecological conditions. Light being one of the factors which determine the photosynthetic process of the plant determines the morphology of the leaves of plants in different habitats and also in single plant species as demonstrated with the red oaks plant species. This can be established by carrying out a biological statistical analysis of the various leaves under different microenvironments. Therefore, in the biological investigations of the morphological variations of leaves, statistical mathematics is a very vital and feasible technique that aids biologists in the description and representation of information logically and rationally. Mean, mode, variance, and standard deviations are some of the main ways of describing biological data and information. The study of leaf shape, surface area, and weight of shade leaves and sun leaves should be furthered to reveal its relation with other environmental factors like water content and humidity.
Data summary
Table
Works cited
Coker Paddy and Kent Martin. Vegetation description and analysis. N.Y: John Wiley and Sons, 1992.
Mantovani, Andre. A method to improve leaf succulence quantification, Biol. Technology 1999: 42:8–10.
Martin Craig. Physiological ecology of the Bromeliaceae. Botany Review, 1994 60:45–75.