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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