Post on 06-Apr-2017
POLLEN APERTURE
AND SYMMETRYPrepared by:
AIRA B. BELLENBSEd 3-P
POLLEN APERTURE
A specially delimited region of the pollen grain wall
FUNCTIONPrimarily 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
HARMOMEGATHYAllows the pollen grain apertures to contract with water loss, effectively sealing the apertures via the surrounding desiccation resistant exine wall
POLLEN APERTURE TYPERefers to the shape, number,
position and arrangement of the aperture of a pollen grain
INAPERTURATE – pollen grains that lack any recognizable aperture
GENERAL TYPES OF APERTURE1. COLPUS an elongate aperture with a length/width ratio of greater than 2:1
can be elliptic, oblong, or fusiform in outline shape
GENERAL TYPES OF APERTURE
2. PORUSa circular to slightly elliptic aperture with a length/width ratio of less than 2:1
Triporate
Diporate
Pentoporate
GENERAL TYPES OF APERTURE3. PANTOPORATEif pori occur globally on the pollen grain surface
GENERAL TYPES OF APERTURE4. COLPORATEshaped like a colpus but has a circular region in the center
GENERAL TYPES OF APERTURE
5. ZONOAPERTURATE /STEPHANOAPERTURATEpollen grains with apertures occurring in the equatorial region
GENERAL TYPES OF APERTURE6. SULCUSan elongate
aperture similar in shape of a colpus but either centered at a pole or more rarely, parallel to the equator
7. ULCUSa circular to
slightly elliptic aperture similar in shape to a porus but occurring at the pole
GENERAL TYPES OF APERTURE
NUMBER OF APERTURESDesignated by appending the prefix mono-, di-, tri-, tetra-, penta-, hexa-, or poly- (more than six) to the terms colpate and porate
RARE & SPECIALIZED APERTURE TYPESSyncolpate A pollen grain in which the colpi are
joinedTrichotomosulcateA three-branched aperture typeSpiraperturateOne or more apertures that are
spirally shaped.
POLLEN SYMMETRYGenerally either radially symmetric or bilaterally symmetric
Often incorporated or assumed as a part of a shape term
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