Competitive Exams: Revision Terminology Part 13

  • 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 -> 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 -> Waxy cutin -> cuticle – reduce water loss & check pathogen

  • Cuticle -> 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.