Pollen and gamete nomenclature

Lee Hadden hadden at WINGATE.EDU
Thu Sep 2 16:26:09 EST 1999


Jon,

As I understand it, the pollen grain is the male spore which is
disseminated, then germinates after landing on appropriate female
structures, grows the pollen tube there and is then considered the
mature male gametophyte.  It is in this male gametophyte that the sperm
cells form, being delivered close to the egg by the ever-growing pollen
tube [the growth controlled by the tube nucleus inside the tube].  So
technically, the pollen is a spore [microspore] which becomes the
sperm-producing male gametophyte after the pollen tube grows.  Inside
the tube another nucleus, the generative nucleus, divides into two sperm
nuclei which then are released from the tube at the right place and
time.  I welcome correction or fine-tuning should my understanding not
be on target.  But I am confident that pollen grains are not gametes,
but are male spores.

You can have students germinate the pollen grains fairly easily by
dusting pollen on large drops of different conc. of sucrose solutions in
petri dishes.  Observe often for several hours [I use an inverted tissue
culture microscope] and pollen tubes will emerge from many of them in at
least one of the sucrose concentrations.  I have used lily [esp.
amaryllis] and Christmas Cactus pollen with great success.  That the
tubes don't grow forever or directionally in the absence of female
chemical cues is easily observed and provides a basis for discussion of
that aspect of plant reproductive physiology.

Lee Hadden
Department of Biology
Wingate University
hadden at wingate.edu.

Jon Greenberg wrote:
> 
> I have been criticized for referring to pollen as the male gamete. How
> do you all handle this issue? Do you say that seed plants have sperm
> cells, and the pollen is simply a structure that carries these gametes?
> 
> Many thanks.
> 
> Jon Greenberg

-- 
MZ



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