Plant Tissue Root Stem Leaf

All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
of 17

Please download to get full document.

View again

  24 PP LLAATTSS  TT IISSSSUUEESS   Classification of plants according to their complexity of their body:a)   unicellular – their body contains 1 eukaryotic cell that is responsible for all living functions b)   multicellular – their body is composed of groups of cells of the same type associate together to form tissues , the cells in a tissue act together to perform common function Histology – is the study of the microscopic structure plant and animal tissue Classification of plant tissues  According to their function & structure: 1.   Ground tissue (is classified according to the thickness of the cell wall)  a.   parenchyma  -   its cells are usually loosely packed, cubed-shaped or elongated-   cells contain a large central vacuole and have thin,flexible cell walls   -   fills internal parts of the plant’s organs-   may be adapted for storage, support, photosynthesis-   e.g. onion bulb, mesenchyme of leaf    b.   collenchyma  -   their cell walls are irregular in shape and thickened atthe corners to provide strength and flexibility   -   support the growing parts of plant   -   e.g.  stem of the fruits of pumpkin or cucumber, stem of  potato, stem of dead nettle   c.   sclerenchyma -   sclerenchyma cells have thick, rigid cell wall-   support the non-growing parts of the plants-   e.g.  pit of plum, apricot   -   there are two types of cells:i.    fibres = cells up to 50 cm long that occur instrands, e.g. linen, flax  ii.   sclereids = thick wall lignified cells that causegritty texture of a pear  2.   Vascular tissue -   carries water and nutrients throughout the plant and helps support the plant-   are typical for higher plants in which they form vascular bundles  -   there are two kinds of vascular tissue:a.   xylem  -   moves water and minerals upward from roots to leaves-   is composed of two types of cells:i.   tracheids – are long, thick, narrow sclerenchymacells with thin separations between themii.   vessel elements – are short, wide sclerenchymacells with no end walls; are wider than tracheidsand more water move through them  Angiosperms   → contain tracheids and vessel elements Gymnosperms   → contain only tracheids   they conduct water when they are deadand empty   alive, containchloroplasts in thecells  25 they are vital cells b.   phloem -   moves sugar or sap in both directions throughout the plant srcinating in the leaves-   contains:i.   sieve tubes – are stacked to form long sievetubes with perforated end walls called sieveplates  ii.   companion cells    – are parenchyma cells thatenable sieve tube tubes to function Types of vascular bundles: 1.   concentrical vascular bundle2.   collateral vascular bundle3.   bicollateral vascular bundle4.   radial vascular bundle    3.   Protective tissue = Dermal tissue -   forms the outside covering of the roots, stems and leaves-   its cell are arranged closely together , there are no intercellular spaces-   has protective function ã   above the ground = epidermis →prevents the plant from drying out byreducing water loss from evaporation, also secretes waxy layer calledcuticle ã    below the ground = rhizodermis → protects the root, forms root hairs  that absorb water and nutrients-   special structures are derived from epidermis for keeping some specific functionsa.   cuticle – thin waxy layer over the epidermis which helpsto reduce water loss b.   stoma/ stomata  – openings in the epidermis that regulatethe passage of gases and moisture into and out of the plant, contain chloroplastsc.   hydathodes – water excreting epidermal structures,thatare formed from the stomata which lost the irability toopen and closed.   trichome = hair - are epidermal outgrowthsi.   glandular –   pelargonium  ii.   stinging –  nettle  iii.   absorptive –    root hair    4.   Meristematic tissue -   contains cells continuously divide → are responsible for plant growth-   forms meristems = growing regions of plants Classification of meristems according to their location: Classification of meristems according to their ability to divide: ã   primary meristems -   derived from apical meristems-   have ability to divide during whole lifea.   dermatogen = protoderm - gives rise to epidermis   b.    plerom – gives rise to vascular cylinder  = stele  c.    periblem    – gives rise to  primary cortex   ã   secondary meristems -   are derived from differentiated cells of mature tissue-   restore their ability to dividea.   vascular cambium – produces vascular tissue – secondaryxylem and phloem b.   corc canbium – produces cork (bark) ã   latent meristem = “resting” meristem  -   is activated during the special conditions, e.g.  pericycle → produceslateral roots  PP LLAATT  OO R R GGAASS   Classification of plant organs according to their function: 1.   vegetative –  roots, stems   and leaves – they provide nutrition and growth 2.   generative –  flowers, seeds and fruits – they provide the production of gametes Root -   root = RADIX-   roots are structures that usually grow underground  Functions : ã   to anchor the plant in the soil   ã   to absorb water, minerals and oxygen from the soil   ã   to transport water and nutrients from the soil to the rest of the plant   ã   to store energy reserves for the plant   ã   gas exchange    Root anatomy:   1 = root cap   –    is a protective covering of the root tip –     produces a slimy substance that functionslike lubricating oil which allows root to moveeasily through the soil as it grows 2 = root tip  –    contains apical meristem 3 = rhizodermis  –     protective tissue of the root –    forms root hairs 4 = cortex  –    is composed of parenchyma cells withnumerous air spaces –    storage place for starch or other metabolites 5 = vascular cylinder = stele  –    is the core of the root –    contains: o    pericycle = 7  o    phloem = 8 o    xylem = 9 o    pith = 10   6 = root hair  –    root hairs are tiny, hairlike structures –    increase the absorpting surface of a rootsystem pith rays = vascular rays (stržňové lúče)radial vascular  bundle
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks