Plant Tissues & Vascular Tissues PDF

Plant Tissues & Vascular Tissues  Tissues A group of closely associated cells that perform related functions and are similar in structure.  Plant Tissues  Tissues in plants that divide throughout their life.  Plant tissues can be classified as:  Growing or Me...

Plant Tissues & Vascular Tissues  Tissues A group of closely associated cells that perform related functions and are similar in structure.  Plant Tissues  Tissues in plants that divide throughout their life.  Plant tissues can be classified as:  Growing or Meristematic tissue  Permanent tissue Permanent tissue Meristematic tissue  Meristematic tissues  The growth of plants occurs in certain specific regions.  This is because the dividing tissue,  Known as meristematic tissue  Composed of actively dividing ceIIs, responsible for the production of ceIIs.  Capacity for division is restricted to certain parts of the plant body called meristems  Which are active throughout the life of the plant body.  Meristematic tissues Kinds of meristems Apical meristems - found at the tip of stems & roots Lateral meristems  found along the sides of roots & stems  increase width or diameter of stems & roots  types: 1. vascular cambium 2. cork cambium Intercallary meristems  found at the bases of young leaves & internodes  responsible for further lengthening of stems & leaves  Permanent tissues Tissues that attained their mature form and perform specific functions.  They stop dividing Types: Simple permanent tissues Complex permanent tissues  Dermal / surface tissue Simple permanent tissues - Consist only of one kind of cells A. Dermal / surface tissue - External tissues - Forms protective covering of the plant body a. Epidermis b. Periderm  Permanent tissues Epidermis - the outermost layer of the primary plant body - covers the leaves, floral parts, fruits, seeds, stems and roots - generally, only one layer thick with cuticle - composed mostly of unspecialized cells, either parenchyma and/or sclerenchyma - contains trichomes, stomata, buIIiform ceIIs (in grasses) Structure of epidermis  Stomata Stomata - pores for gas exchange - present on both surfaces of Leaves.  Cuticle Cuticle – Lines the outer waII of the epidermal ceIIs - made up of waxy material that protects plants from desiccation Cuticle Layer of the leaf  Trichome s Trichomes – outgrowths of epidermal ceIIs  Periderm (Bark) Periderm (Bark) is the outermost layer of stems and roots of woody plants such as trees.  Ground 1. Parenchymatissues - are the general purpose ceIIs of plants - cells are rounded in shape & have uniformly thin walls found in all parts of the plants. - living at maturity, have large vacuoles - location Ieaf, stem (pith), roots, fruits Functions: *basic metabolic function (respiration, photosynthesis & protein synthesis) *storage (potatoes, fruits, & seeds) *wound healing and regeneration Parenchyma  Collenchyma 2. Collenchyma - A specialized parenchyma tissue found in the green parts of the shoot and performs photosynthesis. - differentiate from parenchyma cells & are alive at maturity Functions:  Support & elasticity (stem surfaces & along leaf veins)  Degeneration  ScIerenchyma 3. ScIerenchyma  sclerenchyma cells which are non-living and lack protoplasts at maturity  Have thick, lignified secondary walls  Provide strength and support in parts that have ceased elongating or mature Types 4. ScIereids or stone cells 5. Fibers  Complex Permanent Tissues Vascular Tissues Specialized for long-distance transport of water and dissolved substances. Contain transfer ceIIs, fibers in addition to parenchyma and conducting ceIIs. Location, the veins in Ieaves Types: 1. Xylem 2. phloem  Xylem Xylem GW xyIos w/c means “wood” transports water and dissolved nutrients from the roots to aII parts of a plant. Direction of transport is upward. There are two types Primary xylem – differentiates from procambium in the apical meristem & occurs throughout the primary plant body. Secondary xylem – differentiates from vascular cambium & is commonly called wood. Xylem  Xylem Xylary elements – the conducting cells in xylem - 2 kinds of xylary elements: – tracheids – the only water conducting cells in most woody, non flowering plants. – vessel elements – occur in several groups of plants, including angiosperm. - both are elongated, dead at maturity, lignified secondary cell walls. Tracheids Vessel elements  PhIoem PhIoem - Greek word phloios meaning, “bark” - transports dissolved organic / food materials from the Ieaves to the different parts of the plant - glucose in phloem moves in aII directions Types 1. Primary phloem – differentiate from procambium and extends throughout the primary body of the plant. 2. Secondary phloem – differentiates from the vascular cambium and constitute the inner layer of the bark.  PhIoem Sieve tube elements  main conducting ceIIs of phloem  elongated and non-nucleated  uniformly thin walled with the end walls perforated to from the sieve plate. Sieve tube element are attached end to end to form the sieve tube. PhIoem  Vascular Bundles with xylem & phloem Maize or Corn – vein in cross Alfalfa – vein in cross section section SHOOT APICAL MERISTEM ROOT APICAL MERISTEM