Plant life cycle

Ross Koning koning at ECSUC.CTSTATEU.EDU
Fri Oct 3 11:22:05 EST 1997

At 11:09 AM -0400 10/3/97, Jon Monroe wrote:
>Ross Koning wrote:
>>Ceratopteris spores germinate quickly, develop
>>gametangia rapidly and predictably on 1.5% agar.
>>Wet mounting some female and male-dominant
>>gametophytes under one coverslip will quickly
>>show swimming sperm, and (with the right prep)
>>show them in chemotaxis near archegonium necks
>>and even wriggling down the neck!
>Thanks Ross!  I've never grown these organisms but I will now try.  Upon
>reading this I remembered that I inherited a number of vials of fern and
>moss spores from my predecessor but I have never tried growing any of them.
>Do you Ross, or anyone else have any tips for growing Dryopteris,
>Asplenium, Polypodium, or Polystichum?  How about the moss Polytricum?
>Thanks.  Students will surely develop a stronger interest if they grow the
>plants themselves and then get to take them home...

Les Hickok sent me a vial of spores some years ago...
I'm still using them.  I have had students grow a range
of fern gametophytes from spores over the years.  You
just collect a fertile frond with shedding spores, drop
it in an envelope to dry.  After a week or so, you remove
the frond and the powder in the envelope can be sown
thinly on 1.5%-2% agar.  The agar could be plain or you
could add mineral nutrients.  Knopp's agar is easy to make
and works very well for me.  The plates should be put under
some fluorescent lights in the classroom.  Spore germination
is a matter of days, gametangia form in weeks for many
species of ferns.  Pteridium, Polypodium, Dennstaedia, brake
fern, fertile forms of Nephrolepis, etc. all work quite well.
Onoclea is a tad slower for me, as is Adiantum.  Even my
Equisetum arvensis spores made beautiful gametophytes...I never
got any gametangia though.  With Polytrichum I get protonemata
very quickly, and tiny leafy gametophytes in three weeks.  I
have never arrived at gametangia, though, and that is the key
to "showing" you have a gametophyte rather than a sporophyte.

I keep each Petri dish inside a ZipLok bag to help retain moisture
over this long incubation, but you can also add water to the plate
if you need to.  Free water is needed for sperm release, archegonium
opening, and sperm chemotaxis anyway.  Looking at a population of
Ceratopteris gametophytes in a dish, you DO get the clear impression
about antheridiogens!


Ross Koning                 | koning at
Biology Department          |
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479

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