Cortex trunk is a cylinder-shaped area between the epidermis and the central cylinder. The cortex consists of thin-walled parenchyma tissue. In some plants, stem parenchyma serves as a means of photosynthesis.
a. The composition of the anatomical stem dikotil
Anatomy stem dicotyledonous plant consists of bark, wood, and pith. Pith is very hard to find in an old wooden trunk. The bark of the outer portion has epidermis. In the epidermis there is a cork cambium (felogen). Felogen working outwards to form a layer of cork covering epidermis called felem, while working towards the so-called feloderm. Group epidermal cells are not covered with cork substance called lenticels that serves to evaporation and gas exchange. In the bark there parenchyma tissue, tissue backer, file phloem, reed phloem, accompanist cells and phloem parenchyma. Sklerenkim network is a constituent fibers of the phloem.
File phloem vessels adjacent to the xylem vessels. Among the files xylem and phloem vessels are vessels or cambium cambium fascist. Cambium fascist part that separates the bark. If the location of the phloem and xylem side by side, the type of bond is called collateral vessels. Collateral types are divided into two, namely collateral collateral open and closed. Collateral is called open if there cambium between the phloem and xylem, while the covered collateral, if between the phloem and xylem no cambium. Wood is the part that lies between the fascist cambium pith. Wood is composed of channels (trachea), which is cell death and the location of the interlocking edges. The channel serves to channel water and mineral salts from the roots to the leaves.
In the wood there is trakeid the elongated cell shape, sharp edges, and the smaller size of the trachea. Trakeid function supporting or reinforcing rods. Fascist shaping wood cambium inwards and outwards bark. Wood formation activity is more active than the formation of the bark. This resulted in a larger portion of wood bark.
Wood formation in the rainy season is more active than the dry season. Thus, causing a second difference limit the activity of the formation of the so-called circle of wood. In the country that has four seasons, each year we will get four perimeter years. Pith is the parenchymal tissue that serves to store food reserves. Pith found in young stems. Pith is not found on older stems, because the pith getting lost in line with the increase in diameter of the stem.
b. The composition of the anatomical stem dicotyledonous herbaceous plants
Herbaceous plants, such as legumes, outer epidermis there. Herbaceous plant stems do not have the cork cambium. Anatomy of dicotyledonous stems of herbaceous plants, are not so different, both structure and function. The differences are clear, namely the cambium activity that causes the difference in the phloem and xylem. Number of phloem and xylem formed less. Part of the cortex is composed store food reserves.
c. Anatomy stems of monocots
Monocot stem anatomy is very different from dicotyledonous stem anatomy. The epidermis monocot plants have thick cell walls. Under the epidermis there is a thin tissue that consists of a network sklerenkim which is bark. Bark act to strengthen and harden the outer part of the stem. Vascular bundles spread across the trunk, but most in the areas closer to the bark. Phloem vascular bundles xylem surrounded by side with sklerenkim. Type of vascular bundles is called vibrovassal. At monocots there cambium. Thus, the growth that occurs only extends to enlarge the rod through the establishment so that enlargement of the stem cavity reksigen very limited. Unlike the stem dicotyledonous, monocotyledonous stem anatomy or structure of young and old monocots have exactly the same structure.
0 Response to "Definition of Plant Stem"
Post a Comment