Pteris ppt

Pteris ppt

• 1.
  Systematic position Division :Filicophyta Class : Leptosporangiopsida Order : Filicales Family : Polypodiaceae Sub-family : pteridioideae Common Indian Species P. vittata, P. cretica, P. biaurita, P. ensiformis, P. adscensionis, P. wallichiana etc... Pteris
• 2.
  Occurrence of distribution lCosmopolitanfern being distributed in almost all area. lIt prefers tropical and subtropical climates. lPlants usually grow in well drained places or in crevices of rocks. lThey are very common along the slopes of hills and can be seen at 1200 metre above sea level. lThere are aboubt 250-280 species reported for the genus.
• 4.
  SPOROPHYTE Morphology of Sporophyte lSporophyteis differentiated into root, stem and leaves. lPrimary root is soon replaced by the adventitious roots. Roots are slender, black, wiry and arise from ventral side of rhizome or all over the surface. lStem is rhizomatous, underground, branched, perennial and covered by brown scales. Some species have persistant leaf bases on rhizome.
• 5.
  lLeaves- Macrophyllous, unipinnateor imparipinnate (P. vittata) or Bipinnate (P. biaurita). Arise acropetally on the rhizome. Develped leaves are called fronds. lPetiole base is covered with brown scales and sometimes with ramenta lRachis has several sessile, lanceolate leaflets arranged in pairs except the terminal one. lLeaflet is rough ,has a midrib from which the lateral veins with dichotomous branching arise. Venation is open dichotomous venation. lYounger leaves shows circinate vernation.
• 6.
  Anatomy of sporophyte 1)Anatomy of Rhizome lRhizome is differentiated in to epidermis,cortex and stele lEpidermis-single layered with quadrangular cells,covered by cuticle. lCortex-multi layered,differentiated in to Sclerenchymatous hypodermis and inner broad parenchymatous region. parenchymatous region has root and leaf traces.
• 7.
  lStele-In P. vittatait is dictyostele with a ring of vascular strand (meristele). lMeristele is embedded in the parenchymatous ground tissue. lEach meristele is elliptical with single layered endodermis having casparian strips in its radial walls. l1-2 layered thin walled pericycle is present below the epidermis and surrounding the phloem. lPhloem has only sieve cells and phloem parenchyma. It completely surrounds the xylem.
• 8.
  lXylem is presentat the centre of meristele. It shows central protoxylem surrounded on either side by metaxylem. lIt consists of tracheids and xylem parenchyma.
• 9.
  2) Anatomy ofPetiole or Rachis lIt is differentiated in to epidermis,ground tissue and vascular bundle. lEpidermis-single layered with narrow quadrangular cells coverd by thick cuticle. lSome epidermal cells give rise uniseriate bicellular hairs called as ramenta. lGround tissue-It has multilayered sclerenchymatous hypodermis followed by parenchymatous tissue in which the vascular bundle is embedded.
• 10.
  lVascular bundle-It is'V' or 'U' shaped. lIt resembles meristele and has single layered endodermis with casparian strips. lPericycle is 1 or 2 layered and parenchymatous. lXylem is at the centre with mesarch condition surrounded by phloem.
• 11.
  3) Anatomy ofleaflet lIt has epidermis, mesophyll and vascular bundle. lEpidermis - single layered present on both upper and lower surfaces. It has stomata only on the lower epidermis(Hypostomatous condition). lMesophyll - either homogenous or differentiated in to upper pallisade and lower spongy with broader intercellular spaces. lHypodermal region of mid rib has sclerenchymatous strips in both abaxial and adaxial sides.
• 12.
  lMid rib hassingle concentric, amphicribal vascular bundles surrounded by single layered pericycle and endodermis. lVascular strands are embedded in the mesophyll.
• 13.
  4) Anatomy ofRoot lIt is differentiated in to epidermis ,cortex and stele. lEpidermi-single layered with thin walled cells.A few cells form root hairs. lCortex -multilayered and differentiated in to parenchymatous outer cortex ,sclerenchymatous inner cortex and single layered endodermis with casparian thickenings. lStele -it has single layered thin walled pericycle,central plate like exarch and diarch xylem surrounded on either side by phloem.
• 15.
  REPRODUCTION • Vegetative • Asexual •Sexual