> The pollen tube is the extension of a single cell of the pollen grain
> (or male gametophyte) the tube cell. You can demonstrate that this
> growth does not require any contribution of the style other than
> sucrose, calcium, and boron, since pollen grains of many species will
> successfully germinate in a liquid medium containing these three
> ingredients.
If 'Growth' does imply also -tropism, then there must be 'factor/s' other than
the sucrose, calcium and boron. For the pollen tube does grow dirrectly towards
the ovules...............
