LE3 .A278 2015

2015

Evans, Rodger

Acadia University

Bachelor of Science

Honours

Biology

Biology

Helianthemum canadense (L.) Michx. (Canada Frostweed or Rockrose) is a “red-listed” species in Nova Scotia. Stressors on this endangered plant, including habitat loss and recently discovered seed predation, have potentially caused significant population decline over the past several decades. Studying the developmental reproductive biology of Frostweed provides insight into the role of different flower types in plant reproduction and regeneration. Frostweed is classified as a cleistogamous species because two flower types occur at different times, on the same plant, in the same growing season. The first flowers are chasmogamous (open flower, insect pollinated). Later in the season, on the same plant, cleistogamous flowers (closed flower, self-pollinating) are produced. Initially, the two flower types develop similarly with the exception of higher ovule and anther counts in chasmogamous flowers. It is not until later in development, specifically when the stigma is initiated, when there are notable developmental changes between the two flowers. The most morphologically obvious difference is the presence of petals on mature chasmogamous flowers and the absence of petals on cleistogamous flowers. On a single plant there are approximately 1-2 chasmogamous flowers and 10-60 cleistogamous flowers. Chasmogamous flowers maintain genetic variation within the population and cleistogamous increase reproductive output especially in times when insect pollinators may be limited. A direct impact upon genetic variation in populations may be the presence of the seed predating moth Mompha capella which was found to have infested 50% of developing chasmogamous fruits in one population in 2014. It is unknown what effect this moth will have on Frostweed populations. The comparative data gathered from this study, however, can be used to help researchers better understand how reproductive biology, seed predation, and other stressors affect Frostweed populations.

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https://scholar.acadiau.ca/islandora/object/theses:1192