Structure and Function of Plant Tissue

     Tissue in plants can be grouped into two categories, namely (1) meristematic tissue or embryonic tissue and (2) permanent tissue. Meristematic tissue is the tissue of young active cells constantly divide to form the primary structure on the plant, while the permanent tissue is a tissue that has undergone differentiation. Permanent tissue consists of simple tissue and complex tissue. Simple tissue include parenchymal tissue, chollenchyma tissue, and sclerenchyma tissue. Complex tissue include dermal tissue and vascular tissue.

A. MERISTEMATIC TISSUE
       Meristematic tissue is the tissue cells are able to divide by mitosis continuously (are embryonal) to increase the number of cells in the plant body. Meristematic found in certain parts of the plant. In general, the cells making thin-walled meristematic tissue, and relatively rich in protoplasm. Meristematic cell vacuoles are very small and scattered throughout the protoplasm. This tissue consists of cells that are not differentiated. The ability of meristematic tissue to mitosis continuously causes plants to grow tall and big. Based on where the plant meristematic tissue divided into three types: apical meristematic, lateral meristematic, and Intercalary meristematic.


       Apical Meristematic tissue meristematic tissue is found on the tip of the stem and root ends. Intercalary Meristematic tissue is tissue exists between permanent tissue sections at the base of grass stems. Lateral Meristematic tissue, is tissue usually found around the organs where the tissue is found, such as vascular cambium and the cork cambium. Based on its origin, meristematic tissue is divided into two, that is primary meristematic and  secondary meristematic.

a. Primary Meristematic
    Primary meristematic is Meristematic growing directly from embryonic tissue (embryos) that divide mitosis and produces primary growth in plants, causing plants to grow taller. Examples of primary Meristematic is apical Meristematic at the end of the stem and root ends.

b. Secondary Meristematic
    Secondary meristematic is meristematic that develops from the tissue that have undergone differentiation. Secondary meristematic tissue will produce secondary growth that causes the stem becomes larger as the activity of vascular cambium stem dikotil plant will produce timber vessels (xylem) to the inside and filter vessels (phloem) to the outside. In addition, there is a cork cambium (felogen) are also part of is called secondary growth periderm. Cork cambium consists of three parts:
1) felem, the cork tissue itself is composed of dead cells
2) felogen, is part of the cork cambium leading to the outside to form felem
3) feloderm, is formed part vang felogen inward and is similar sifatnva parenchymal tissue and consists of living cells. 




B. PERMANENT TISSUE
      Permanent tissue consists of two groups, is simpel tissue and complex tissue. Simple tissue consists of three kinds, namely parenchymal tissue, chollenchyma tissue, and network sclerenchyma. Complex tissue composed of two types, is epidermal tissue and vascular tissue.

 1. Simple Tissue
       Simple tissue in plants is the dominant tissue that builds a plant. simpel tissue functions are very wide, such as a place to store food reserves, as a proponent of plant tissue and as a venue for photosynthesis.

a. Parenchyma tissue 
      Parenchymal tissue is tissue that is found in all parts of a plant. The characteristics of parenchymal tissue was (1) made up of living cells that are still active, (2) its constituent cells have primary walls that are relatively thin and flexible, generally do not have a secondary wall, (3) at the center of the cells contained vacuoles large, (4) the size of the cells, (5) cells located relatively rare and rich space between cells, and (6) having a complete cell organelles. Parenchymal tissue is the tissue that fills most of the woody parts of plants, such as the center of the stem, the leaf that serves to photosynthesis, and the peripheral roots.

     Based on the function, parenchyma tissue is divided into several types, namely: assimilation parenchyma, hoarder parenchyma, water parenchyma, and air parenchyma. Assimilation parenchyma (klorenkim) usually located at the edge of an organ, such as the leaves, green stems, and fruit. Parenchyma in the leaf called the mesophyll, palisade parenchyma consists of (fencing parenchyma) and spongy parenchyma. In the mesophyll cells contained chloroplasts, which plays an important role as a venue for the process of photosynthesis. Hoarder parenchyma usually located on the inside of the body, for example: the pith of the stem, root tubers, bulbs, rhizomes (rhizome), or seeds. Inside the cells there are food reserves in the form of sugars, starches, fats or protein. Water parenchyma, present in plants that live in hot regions (xerofit) to deal with the dry period, such as the cactus and aloe vera plants. Air Parenchymal (aerenkim), the space between selnva large, round constituent cells as a float in the water, such as parenchyma in the petiole of water hyacinth plants.

 b. Collenchyma Tissue
      Collenchyma consists of living cells are more or less elongated, thickened walls of pectin substances, especially in the corners of the cell, not lignin and elastic, that is capable of stretching but are unable to return to normal if the organs grow and function as a network supporting the organs begin to grow or still easy. In herbaceous plants even in adult organs. Collenchyma may contain chloroplasts, found in stems, leaves, flower parts, and fruits. Collenchyma usually formed just below the epidermis

c. Sclencerhyma Tissue
    Sclencerhyma is a proponent tissue of plant, the cells undergo secondary thickening with lignin and exhibit elastic properties. Its main functions are supporting, but sometimes also as a protector. Sclencerhyma divided into two types, namely fiber and sklereid. Fiber cells are long and narrow with pointed toes, is generally arrange transport network. Sklereid very thick walled and berlignin, also called stone cells are composed of cells short, for example in a coconut shell, nut shell.

2. Complex Tissue
a. Dermal Tissue

    Dermal tissue functions covering the surface of the plant body, such as the epidermis. The epidermis is the outermost tissue that covers the surface of plant organs, such as leaves, the flowers, fruit, seeds, stems, and roots. Sometimes found in the epidermis cuticle. On the outer surface of the cuticle are sometimes found waterproof waxy coating to reduce water evaporation. The main function is as a protective epidermal tissue tissue in the inner.

     Epidermal tissue composed of living cells that form flat with surface top and bottom sides parallel but may be composed of irregular, often equipped with a cuticle or wax. Epidermal cells are compact and do not have the space between cells. In some plant species become modified epidermal scales or feathers, trichomes, root hairs and stomata. Generally, epidermal cells do not contain chlorophyll.

     Stomata are slit / small mouth on the leaves of plants. Stomata in general is on the bottom surface of the leaf, but for some aquatic plants like lotus, its stomata is on the top surface to assist in the exchange of gases and the evaporation.
 
     Trichomes are additional tools that a bulge / hair in the epidermis. Can be found in various plant organs such as leaves, stems, flowers, fruits, roots. In leaf trichomes serve to reduce the amount of evaporation, reduce interference animals / humans, and forward excitatory (trichomes are rich plasma). At the root there are root hairs that serve to expand the uptake of water and nutrients. In the flower there are nectar the function to issue honey attracts insects to pollinate. In seeds are hairs that make seeds become light and easily blown by the wind and thus help in seed dispersal, prevents insects that would damage the seeds, soak up water so seeds germinate and grow quickly, the stem to reduce evaporation and to climb as the rattan . 

b.  Vascular Tissue
     Vascular tissue serves to carry out transport functions in plants. This tissue is a complex tissue composed of xylem and phloem . Both groups of xylem and phloem, in the body of vascular plant forming beam vascular that is located parallel to the axis of the organ into place.

1). Xylem
     Xylem is a complex tissue because it is composed of several different cell types. Its main constituent is trakeid and trachea as a water carrier channels with thickened cell walls thick enough also functions as an advocate. Xylem is also made ​​up of fibers, sclenchyma and parenchyma cells which alive and involved in various metabolic activities of cells. Xylem also known as vascular wood that make up the wood on the stem.

     Trakeid and trachea are two groups of cells that build the xylem vascular. Both types of cells elliptic, secondary walls of lignin and contains no protoplasm thus form of cell death. The fundamental difference between the two, is on trakeid not any perforations (holes), there is only a gap (dots), in the form of plasmodesmata that connect one cell to another cell. While there are perforation of the trachea at the ends of the cell. Transport of water and minerals in the trachea takes place through these perforations, while trakeid lasts through the dot (gap) between cells . Trachea cells forming structured such that a row of cells elongated (ends meet ends) to form a long tube (capillary). Thickening of the tracheal wall shape can be a spiral ring, or mesh.

      Based on the formation, xylem is divided into two types: primary xylem and secondary xylem. Primary Xylem is the xylem which is formed from the differentiation of stem apical meristem, which prokambium. Primary Xylem consists protoxilem and metaxilem. Secondary Xylem is formed from the cambium xylem vascular.

2) Phloem
     Phloem vascular or filter vascular is complex tissue, consisting of vessel components (reed filter), accompanist cells, albumin cells, parenchyma and fibers. The most distinctive trait of the filter element is the filter area in the cell wall and the core is lost.

     Phloem vascular also known as filters, which form the bark on the stem. Elements making up the phloem vascular consist of two forms, namely: sieve plate that has many pores, and sieve tubes of similar pipes. Outside of phloem vascular any cells that are still alive which called companion cells. Phloem serve to transport of photosynthesis from the leaves to all parts of the body. Unity between the xylem and phloem  will form bonds fascists vascular.