Structure and Function Trunk

B. Structure and Function Trunk

We often think that the stem was always on top of the soil and the roots under the ground. But there are some species that are underground stems. So, how to differentiate the stem root is to look for bud-bud. The bud is growing point rod is protected by scales. The scales will fall when the stem is formed. But there is also the buds are not protected by scales. The buds can be divided into two, namely, bud stem end (terminal bud) and bud armpit (axillary buds). Terminal buds are at the ends of the rod are still in the growth, while the axillary buds contained in the armpit leaves and on certain roads in the trunk. Bud, in some particular plants, will be dormant if poor environmental conditions, but it can grow again when the environmental conditions are good.

There is also a horizontal stems that grow in the ground with short internodes and leaves yan-shaped scales. This rod is called rhizomes. Rhizomes serves as a food reserve storage. Examples of plants that have rhizomes are ginger, turmeric, galangal, and kencur.
1. Structure Trunk

Stem structure can be seen from outside the structure (morphology) and inner structure (anatomy).
a.Morfologi (External Structure) Trunk

The morphology of the stem of each plant is different. As long stems that are not the same. Some are long and some short. It is influenced by the nature of the genetic and environmental conditions, such as temperature, light, and soil fertility. Thus, plants of the same type will have a different stem lengths for different environmental conditions. Based on the state of the trunk, there are two groups of higher plants. Namely, herbaceous (soft plants) and woody plants. In both the existing plant leaves around the stem. In the trunk there is a node / books (meletaknya leaf spot) and internodus (area in anatara 2 books).

     In general, the soft stems of herbaceous plants, green, have a little woody tissue or none at all, the size of a small trunk, and its age is relatively short. Examples are corn, spinach, sunflower, spinach, and beans.
     While woody plant stems are usually hard and relatively long age. In the old trunk, there is a thick bark and small holes (lenticels) on the surface so that oxygen can get into the stem cells in diffusion. Oxygen was used to breathing process.

b. Anatomy (Structure In) Trunk

There are anatomical differences between the stems of herbaceous plants and woody plants.

     On the outside of the stem of herbaceous plants, which are epidermal cells are thin, there stomata. Then, under the epidermis cells of the cortex. Photosynthesis can take place in the trunk because the cortical cells have chlorophyll. This herbaceous plant stem has no woody tissue and does not contain cork, but it has a network of advocates. Network advocates, namely kolenkim and sklerenkim, is the cause stems of herbaceous plants able to sustain the leaves and upright.
     In woody plant stem epidermis, cortex and stele.

     Edpidermis stem consists of a single layer of cells are compact and not hollow. Epidermal cell walls were covered with a thick cuticle. The epidermal layer acts as a protective layer for the layers in it.
     Parenchymal tissue stem cortex is composed of several layers of thin-walled cells that have a large vacuole. Cortex has cavities / spaces between cells that function to the air exchange. In the cortex are floeterma. Floeterma is the deepest layer of the cortex that has a distinctive shape and composition, and contains grains of starch. Cortical function in the majority of plants is as a food reserve storage. The cause of the cortex are not apparent on the stem monocot plants are spread irregularly veins bond.
     Stele / Cylinder center is the deepest part of the stem. On the stele are xylem (wood vessels) on the inside and phloem (filter vessels) on the outside. In dicotyledonous plants are cambium between the xylem and phloem, whereas monocot plants do not have the cambium. This cambium which causes stem dicotyledonous plants grow. The cambium tissue, which consists of cells that constantly divide, separating the stem bark of another. Part of wood in the trunk thicker than on the skin because of the activities that make up the cambium cells xylem (wood) in the direction of greater than activities forming cells of the phloem (bark) outward. Cambium activity is affected by the availability of water and minerals, so the wood vessels produced during the rainy season bigger and more than that generated in the dry season. So, there are limits indicate the cambium activity during the rainy season and dry season in dicotyledonous plant timber. These limits are called the circle in which the plant is showing its age. Then, the inside of the stele is a core part of the most extensive in the trunk. There is also a radial lines that appear from the center toward the bark is called the radius of the pith. The radius of the pith is traversed by water and nutrients moving to the side. Pith is difficult to distinguish from the pith of the fingers monocot plants.

2. Differences Trunk Dikotil and Monocots

The difference between the stem and monocot plants are as follows:

     Dicotyledonous plant stems branching, whereas plants monokitl unbranched stem and straight.
     Dicotyledonous plants have cambium which enlarge the plant stem, while monocot plants do not have the cambium.
     Location of freight vessels dicotyledonous plants regularly in the form of a circle, while the location of the transport vessel in monocot plants spread.

3. Function Trunk

Trunk has the following functions.

     Serves as the organ track and mineral water from the roots to the leaves, and the trajectory of nutrients from the leaves to all parts of the plant as a result of photosynthesis.
     Forming organs and acts as the buffer leaves
     In some particular plants, stem is a place to store food and vegetative propagation tool.