The lab exercise about External Structure of roots and stems enabled us to see and hold the parts of the roots and stems of plants, thus examine them more closely. We were able to compare the different root systems and the kinds of stems of different plants, thus we were able to find similarities and differences. We examined different root systems and labeled the parts, thus we were able to differentiate both kinds of systems from one another. We were also given the chance to examine closely a monocot and a dicot plant. Thus, we were able to sketch and label the parts, allowing us to further see the similarities and differences between the two. Overall, we were able to successfully label the parts in spite of the discrepancy in time allotted for the experiment.
Imagine a mountain that has no grass, no trees, and no plants. There would be no support for the soil, for there are no roots that hold it together. Soon, there would be soil erosion and poof! The mountain will be gone before you even notice it. Different kinds of plants have different structures of roots and stems in order to function properly. They have systems designed especially for their survival and reproduction. Such examples are the stamen, roots, etc.
Since the needs of different plants completely differ from one another, their parts will surely become different, and this contributes to the wonderful diversity around us. Hopefully, through this exercise, the students would be able to grasp a deeper understanding of the importance of plants around us. Just like the example above, soil erosion can kill thousands of people and can affect the lives of millions more if young individuals such as the students would not become aware of preserving nature. Also, by becoming familiar with the diversity and uniqueness of plants, students would hopefully realize the unique potentials of different plants. The objectives of this exercise are to introduce the students to a world of the plant kingdom and also instill some understanding about the importance of these organisms especially for our survival.
Materials and Methods
Examine the root system of a tap root plant. Sketch it and label its parts. Examine Carabao grass. Compare it with the tap root plant. Sketch it and label parts.
Examine a Talahib and label/sketch it. Try removing the leaf sheath in order to see what it covers. Take note of the parts of the talahib and how each part functions.
Examine a Hibiscus plant and sketch it. Label its parts. Compare it with the Talahib plant. Try to see similarities and differences.
Examine a root tip. Label the different regions and sketch it. Identify the different functions of the regions of the root tip.
Refer to data sheet
There are two types of root systems, the taproot and the fibrous. Among the two, the root system better adapted for anchorage is the fibrous root system. In a fibrous root, the main or primary root branches out profusely in interconnecting a network of fine roots. This type of system enables the plant to be blown down easily, but is provided with a resisting force to being uprooted. One example is grass. Its fibrous roots interrelate with other fiber roots in a large volume of soil particles. Meanwhile, in a tap root system, the main plant root grows in length and girth. However, there is very little branching going on. This root system provides very little resistance to uprooting.
Besides the taproot and fibrous root systems, there also exist different root systems, like the buttress and prop roots. The buttress root system is adjusted to support large tropical trees. Despite the poor soil quality in tropical lands, these trees still survive through the hurricanes and typhoons. The woody roots expand vertically forming radial walls extending out from the sides of the trunk, forming a structure known to architects as a buttress. They cover a large surface of soil. Prop roots deviate from stem nodes like adventitious roots do. They arch out over the soil and branch out some distance away from the trunk. They seem to form a structure that props the tree over a surface of soil, like a tripod that reaches a long distance underground. They also enable the plant to withstand natural calamities like typhoons. (http://koning.ecsu.ctstateu.edu/Plant_Biology/roots.html
There are two main classes in plants, the monocot and the dicot. One basis for distinguishing one from the other is by the number of cotyledons it has in its embryo. This is where they get the names "monocotyledon" and "dicotyledon." The monocot plants tend to have a number of parts divisible by three (three, six, etc.) while dicot plants have parts in multiple of four and five. Monocots have leaf veins that are parallel to the length of the plant and dicots have veins that reticulate. Most dicots have roots that grow out from the radicle region. From the radicle, an apical meristem develops which produces root tissue. Meanwhile, monocots have roots that are adventitious. They branch out from nodes in the stem. Monocots also do not have the ability to have a secondary growth, and thus they do not generate wood. Some examples of these monocots are palms and agaves. (http://www.ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html
) These are just some of the characteristics that differentiate a monocot plant form a dicot plant. Botanists and scientists have used these known characteristics in identifying one plant from another, as in a dichotomous key. Knowing these characteristics of certain plants will better inform us in knowing more about the plant world.
A root tip mainly has 4 regions. The root cap is the most outer surface of the regions. It has outer cells which are loose and breaking away. It basically originates from the meristem. Next to it is the region of cell division where cells mainly undergo mitosis and reproduce. This is called the meristem. Next in line is the region of cell elongation. It is where major change in increase in the length of cells happens. Cell enlargement, a significant part of growth, involves the deposition of additional cell wall material, increase in the amount of cytoplasm, and a substantial boost to the size of the vacuole of the cell. Lastly, there is the region of cell differentiation. Various cell types occur in this region.
There are basically two types of root systems, namely the tap root and the fibrous, and the latter being the better one in terms of anchorage. There also exist different kinds of root systems that enable the plant to withstand changes in weather conditions. There are also two types of stems, namely monocot and dicot. There are differences in the characteristics of the monocot and the dicot, but there are also similarities as well. One example is the presence of nodes and internodes on both kinds of stem. There are 4 regions in a root tip. The root cap, the meristem, where cell division occurs, the region of cell elongation, where cells become longer and less opaque, and the region of cell differentiation where the difference among the different cell types in the mature root become visible.