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POLLEN APERTURE AND SYMMETRY (PLANT SYSTEMATICS 2nd Ed)

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PALYNOLOGY

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POLLEN APERTURE AND SYMMETRY (PLANT SYSTEMATICS 2nd Ed)

  1. 1. POLLEN APERTURE AND SYMMETRY Prepared by: AIRA B. BELLEN BSEd 3-P
  2. 2. POLLEN APERTURE A specially delimited region of the pollen grain wall
  3. 3. FUNCTION Primarily to serve as the site of formation of a pollen tube exiting from the pollen grain body To allow volume changes of the pollen grain with changes in water content
  4. 4. HARMOMEGATHY Allows the pollen grain apertures to contract with water loss, effectively sealing the apertures via the surrounding desiccation resistant exine wall
  5. 5. POLLEN APERTURE TYPE Refers to the shape, number, position and arrangement of the aperture of a pollen grain INAPERTURATE – pollen grains that lack any recognizable aperture
  6. 6. GENERAL TYPES OF APERTURE 1. COLPUS an elongate aperture with a length/width ratio of greater than 2:1 can be elliptic, oblong, or fusiform in outline shape
  7. 7. GENERAL TYPES OF APERTURE 2. PORUS a circular to slightly elliptic aperture with a length/width ratio of less than 2:1
  8. 8. Triporate Diporate Pentoporate
  9. 9. GENERAL TYPES OF APERTURE 3. PANTOPORATE if pori occur globally on the pollen grain surface
  10. 10. GENERAL TYPES OF APERTURE 4. COLPORATE shaped like a colpus but has a circular region in the center
  11. 11. GENERAL TYPES OF APERTURE 5. ZONOAPERTURATE /STEPHANOAPERTUR ATE pollen grains with apertures occurring in the equatorial region
  12. 12. GENERAL TYPES OF APERTURE 6. SULCUS an elongate aperture similar in shape of a colpus but either centered at a pole or more rarely, parallel to the equator
  13. 13. 7. ULCUS a circular to slightly elliptic aperture similar in shape to a porus but occurring at the pole GENERAL TYPES OF APERTURE
  14. 14. NUMBER OF APERTURES Designated by appending the prefix mono-, di-, tri-, tetra-, penta-, hexa-, or poly- (more than six) to the terms colpate and porate
  15. 15. RARE & SPECIALIZED APERTURE TYPES Syncolpate A pollen grain in which the colpi are joined Trichotomosulcate A three-branched aperture type Spiraperturate One or more apertures that are spirally shaped.
  16. 16. POLLEN SYMMETRY Generally either radially symmetric or bilaterally symmetric Often incorporated or assumed as a part of a shape term
  17. 17. THANK YOU!

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