This thesis describes (1) a simple and effective method for growing large numbers of fern gametophytes under field conditions and (2) the application of this method to investigate the sequence and timing of events in the fern life-cycle following spore dispersal or soil disturbance at different times of the year. Long-term field experiments involving <i>Athyrium filix-femina</i>, <i>Blechnum spicant, Polystichum setiferum</i> and <i>Phyllitis scolopendrium</i> were initiated at 2 sites near Edinburgh in January and October 1988. During these experiments (which continued till January 1990) both sites experienced a series of exceptionally mild Winters. The results for the 4 species were strikingly similar. Spores sown in January germinated in the Spring and gametophytes became sexual in the following year between mid-Spring and mid-Summer. Germination was synchronous although many spores did not produce gametophytes. Gametophytes quickly became 2-dimensional; no protonemata were observed. Sex organs developed and matured rapidly and their production was continuous. Most populations consisted of male, female and bisexual gametophytes. In general, female gametophytes were larger than bisexual gametophytes and all archegoniate gametophytes were larger than male gametophytes. All archegoniate gametophytes were meristic; all male gametophytes were ameristic. Most populations were predominantly male. Female gametophytes were always more abundant than bisexual gametophytes. All bisexual gametophytes were protandrous. Fertilization was often rapid, often occurred at high frequency and was not seasonal. Polyembryony was rare. All gametophytes from the January sowing survived the Winter of 1988/'89 but male and fertilized archegoniate gametophytes began to die in the Spring or Summer of 1989. No sporelings died. All gametophytes and sporelings from the October sowing survived throughout the experiment. A third (short) field experiment involving <i>A.filix-femina</i>, <i>B.spicant</i>, <i>P.setiferum</i>, <i>P.scolopendrium</i>, <i>Dryopteris affinis</i> subsp. <i>borreri</i>, <i>Dryopteris dilatata</i>, <i>Dryopteris filix-mas</i> and <i>Pteridium aquilinum</i> was initiated in August 1989. Spores of all 8 species germinated more or less immediately but only gametophytes of <i>P.aquilinum</i> became sexual before Winter. In one population fertilization occurred before the end of the year.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:653925 |
| Date | January 1992 |
| Creators | Lindsay, Stuart |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/15219 |
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