Pollen and gamete nomenclature

[David Starrett]

At 02:26 PM 9/2/99 -0700, Lee Hadden wrote:
>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.
>

I teach it as: Pollen grains derive from the microspore.  Even "immature",
they are multinucleate, and thus not the spore, but the microgametophyte.


Dave


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