Spore production is the
asexualstage
in the fern's life history. The plant producing the spores is called
the sporophyte.
If spores land in a suitable
environment, they germinate, and this marks the start of the sexual
stage in the plant's life history, the plant produced is called the
gametophyte.
(Move
the mouse over the picture for label)
The image on
the right was taken about 5 weeks after I sprinkled fern spores onto compost.
With the naked eye, it looks as if the surface is covered with a green
slime. Under the stereo microscope however, it is possible to see the
gametophytes or prothalli. Move the mouse over the picture
to see a magnified image of the prothallus, a heart shaped structure,
on which the male and female parts of the plant can be found.
After several more weeks,
the prothallus is more obvious and can be seen to have tiny rhizoids
which absorb water and provide anchorage.
Below right is a living
prothallus, about 2 months old and, on the left, one on a prepared
microscope slide.