NET, IAS, State-SET (KSET, WBSET, MPSET, etc.), GATE, CUET, Olympiads etc.: Revision Terminology Part 13

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  • Phloem fibres = Bast fibre – present in second xylem
  • Xylem fibres = intraxylary fibres
  • Xylem
  • (1) Tracheid – dead – most primitive (Bordered pit – gymnosperm, angiosperm, wood vessel of angiosperm) .

(2) Vessels – dead – Conducting units – advanced

(3) Parenchyma – living – short distance transport – Tyloses (outgrowth)

(4) fibres – dead – mechanical support

  • Primitive vessel less angiosperm – Winteraceae, Trochodendraceae, Tetra-centraceae.
  • Vessels present – pteridophytes – Selaginella (spike mosses) , Equisetum, Actiniopteris , pteridium, Regnellidium, Marsilea
  • Vessels present – Gymnosperm – ephedra, gnetum, Welwitschia.
  • Phloem lepton = soft walled conducting
    1. Sieve tube – nucleus absent (1) & (2) = sister cells
    2. Companion cell – sieve tube dependent (analogous albuminous cells of conifers) .
    3. Parenchyma – living (absent in monocot)
    4. Fibres – mechanical support – dead
    5. Sclereids – in older phloem – mechanical support.
  • Slime plugs – Coagulation of slime bodies on sieve plates made of p-protein movement of metrical & sealing of wounds.
  • Fibers – Secrete latex
    1. Latex cell – simple, non – articulated, not fused, Apocyanaece, Ascelepiadaceae, Enphorbiaceae, Moraceae.
    2. Latex vessel – articulated, Papaveraceae, Caricaceae, Compositaer, Musaceae.
  • Latex Heavea Brasiliensis (para rubber) & manihot glaziovi β‡Ύ beleng to Euphorbiaceae
  • Indian rubber – ficus elastica
  • Latex cell – cannabis, Venea minor, Urticodioica
  • Latex of papaya – papain
  • Latex of poppy – morphine
  • Latex of banana – tannin
  • Hydathodes Guttation made of loosely arranged parenchyma cell = epithem
  • Intercellular space = Schizogenous cavity – resin duct
  • Gland secreting oil = osmophores.
  • Epidermis (Angiosperm) can be either Single layered = uniseriate – most angiosperm or Multi layered = multiseriate = Nerium, ficus.
  • Epidermis β‡Ύ Waxy cutin β‡Ύ cuticle – reduce water loss & check pathogen
  • Cuticle β‡Ύ absent In Hydrophytes, roots, underground parts.
  • Root – unicellular hair
  • Stem – multicellular hair
  • Epidermis in cystolithes = lithocyst
  • Epidermis of garlic, Scales & seed of pea & bean = Sclereids
  • Epidermis usually colorless but green due to chlorophyll.