Degree Name

Master of Science (MS)

Semester of Degree Completion

1997

Thesis Director

Elizabeth Harris

Abstract

Experiments were conducted on sporocarps of Marsilea quadrifolia L. to determine whether temperature had any influence on the length of the reproductive period and initial sperm emergence from microgametophytes. Data were then compared to results of similar studies undertaken with the species M. vestita Hooker and Greville to determine whether there was any variation between them. A slight variation was recorded, ranging from 1 to 1.5 hours for initial emergence.

An additional set of experiments was performed with 58 year old sporocarps and approximately two-year-old sporocarps of M. quadrifolia. A difference of 2-6.5 hours for initial sperm emergence occurred between the two collections, suggesting that age did have an effect on the onset of emergence.

Sperm population life spans were also monitored, as well as individual sperm life spans, and it was found that a range of 25-30°C was the optimum temperature for sperm survival. Variation in sperm population life spans was also shown between the 58 year old and two-year-old collections, with an average range of 1-1.5 hours. Life spans for individual sperm averaged 45 minutes in all experiments.

An additional test was performed to see if the presence or absence of light had any effect on the time of sperm emergence. The experiment was conducted on sporocarps of M. quadrifolia at 25°C. It was determined that illumination was not a factor in the process of sperm emergence. Sporocarps of additional species of Marsilea were obtained from the Missouri Botanical Garden and tested for variance in sperm emergence periods. The experiments were performed at 25°C and yielded no viable sperm from the four additional species tested.

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