2/17/2010




                                       Tissues included
                                        •   Vascular...
2/17/2010




                                                                    General structure of VC
Identify immedia...
2/17/2010




Ray initiation                                        Cambial activity
• Single cell may be cut off the side...
2/17/2010




Wood parenchyma
• Axial parenchyma
• Ray parenchyma– have secondary walls

OR
1. Storage parenchyma
2. Speci...
2/17/2010




                                                     • Heartwood– more resistant to decay
• Sapwood/ alburnu...
2/17/2010




Horizontal system
• Ray parenchyma and Ray tracheids
• How do you distinguish between the two?
• Homocellula...
2/17/2010




Arrangement of vessels
• Diffuse porous
  > vessels~ equal diameter and uniformly
  distributed
• Ring porou...
2/17/2010




Rays                            Secretory structures
• Parenchyma cells only         • Laticifers
• Procumbe...
2/17/2010




Sieve cells
• Ends overlap one another
• More sieve areas at point of overlap

Parenchyma cells (excluding a...
2/17/2010




      10
Upcoming SlideShare
Loading in …5
×

Vc 2 X 2 P Secondary Body Of The Plant

2,215 views

Published on

1 Comment
1 Like
Statistics
Notes
  • very neat and very helpful.......... great slides!!
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Views
Total views
2,215
On SlideShare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
79
Comments
1
Likes
1
Embeds 0
No embeds

No notes for slide

Vc 2 X 2 P Secondary Body Of The Plant

  1. 1. 2/17/2010 Tissues included • Vascular cambium • Secondary xylem Secondary Body of the plant • Secondary phloem • Periderm General development Vascular cambium (VC) • Type of meristem? • Which groups of plants have it? • Function? • Location? • Type of cells comprising it? Cell types • Fusiform initials • Ray initials 1
  2. 2. 2/17/2010 General structure of VC Identify immediate origin of the ff: • Phloem ray • Intense vacuolation • Tracheary elements • With primary pit fields • Fibers with plasmodesmata p • Phloem parenchyma • Radial walls thicker than tangential walls • Xylem parenchyma (result of what type of • Ray parenchyma direction?) • Ray tracheid Cambial zone—but there’s only 1 layer Procambium vs Vascular cambium of VC • Gabled endings • Flat endings -- wide if cambium is active • Stain deeply • Protoplasts do not stain • Not differentiated into long strongly and short cells • With fusiform and ray initials 2
  3. 3. 2/17/2010 Ray initiation Cambial activity • Single cell may be cut off the side of a fusiform • Tropical –active throughout the entire life of initial plant • Cut off the end • With definite seasonal climates—ceases with the onset of unfavorable condition • Reduction to a single ray • Segmentation by transverse divisions Resumption of cambial activity usually consist of 2 stages 1. Cambial cells expand radially 2. Cells begin to divide -- bark is easily peeled off Types of cambium Addition of new fusiform initials • Storied – longitudinal anticlinal division • Non-storied– oblique, pseudo-transverse, anticlinal divisions followed by intrusive growth Secondary xylem (2X) = wood • Vertical system • Horizontal system Origin? Cell components? 3
  4. 4. 2/17/2010 Wood parenchyma • Axial parenchyma • Ray parenchyma– have secondary walls OR 1. Storage parenchyma 2. Specialized vessel associated cells or contact cells • Forms protuberances which penetrate through pits into the vessels after becoming inactive or vessels were injured—TYLOSIS or TYLOSES Features of the rays • Length, width, height • Length --XS • Width (no. of cells in a horizontal direction)– TS (no direction) • Height – TS; parallel to the longitudinal axis (no. of cells or um) Uniseriate– one cell wide Biseriate – 2 cell wide Multiseriate– more than 2 4
  5. 5. 2/17/2010 • Heartwood– more resistant to decay • Sapwood/ alburnum--contains living cells and -- result of pathological conditions active in the transport of water -- connected with ageing • Heartwood/duramen- dead cells and ceases to conduct water > disintegration of protoplasts > loss of cell sap > removal of reserve materials > formation of tyloses >oils, gums, resins, tannins, colored subs (oxidation; polymerization of phenols), aromatic cpds > gymnosperms-- aspirated 2X of Gymnosperm Vertical system • Tracheids • Homogeneous • Latewood ---f iber-tracheids • Small amount of • Absence of libriform fibers parenchyma • Tracheids overlap each other >Pits are numerous at the ends of tracheids • Crassula– thickenings of the middle lamella and primary walls • In Pinus, axial parenchyma--epithelium 5
  6. 6. 2/17/2010 Horizontal system • Ray parenchyma and Ray tracheids • How do you distinguish between the two? • Homocellular and heterocellular • Uniseriate ; more than one cell wide with resin duct • Ray parenchyma + tracheids > half bordered pit pairs (cross field) • In Pinus, fenestriform pits Resin ducts • Vertical and horizontal system • Schizogenous development • Tylosoids – enlargement of epithelial cells; blocks resin ducts • Usually produced as a result of injury 2X of Dicotyledon (Angiosperm) • More complex • Vessel members, tracheids, fiber-tracheids, libriform fibers gelatinous fibers, wood fibers, fibers parenchyma, rays • Growth rings > tropical origin—not distinguishable > temperate – distinguishable • Early wood and late wood 6
  7. 7. 2/17/2010 Arrangement of vessels • Diffuse porous > vessels~ equal diameter and uniformly distributed • Ring porous > of different diameters > more advanced > usually in xerophytes Arrangement of axial wood parenchyma • Apotracheal • Paratracheal >scanty >unilateral > vasicentric 7
  8. 8. 2/17/2010 Rays Secretory structures • Parenchyma cells only • Laticifers • Procumbent and upright • Ducts and cavities (traumatic) cells • Homogeneous or homocellular • Heterogeneous or heterocellular Two systems • Vertical > sieve elements, phloem parenchyma, phloem fibers Secondary Phloem • Horizontal > phloem ray parenchyma Origin? Cell components? • arrangement of tissue –determined by nature of cambium (as in the xylem) • Function? • Near the camibum – phloem rays and xylems Conifer Secondary Phloem rays are equal in size • Relatively simple • Mature outer portions – increase in width • VERTICAL SYSTEM > lateral expansion of > sieve cells parenchyma cells including cells, existing cells (radial cell albuminous cells and fibers division)—dilated • HORIZONTAL SYSTEM > uniseriate; parenchyma cells only 8
  9. 9. 2/17/2010 Sieve cells • Ends overlap one another • More sieve areas at point of overlap Parenchyma cells (excluding albuminous cells) • (vertical) storage ( ) g Pinaceae - Secondary phloem contains NO FIBERS Secondary phloem • Resin ducts may be present • Narrow zone of phloem may be active • Collapse of sieve cells of nonconducting phloem >Rays become wavy Dicot secondary phloem Nonfunctioning or nonactive phloem • Presence of • VERTICAL definitive callose > sieve tube members, companion cells, • Disintegration of the p parenchyma cells, fibers y , protoplast t l t • HORIZONTAL >variously sized rays; parenchyma only • Collapse and crushing of Parenchyma—may contain crystals elements Fiber-sclereids—do not develop directly from fusiform cambial initial; parenchyma cells of nonfunctioning phloem 9
  10. 10. 2/17/2010 10

×