Biosystematics and life history strategies of Scentless Chamomile (Matricaria perforata Merat) in Canada
Woo, Sheridan Lois
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The objectives of this thesis were to investigate the biosystematics and life-history strategies of Matricaria perforata Merat in Canada, giving emphasis to the taxon from the Prairies. Literature on the nomenclature of the Matricaria genera was surveyed and reviewed. Matricaria perforata Merat was accepted as the name for the Canadian species under study. Other Matricaria taxa were identified and the synonymy of these species was summarized. The taxonomic characters used to distinguish Matricaria from other genera and separate M. perforata from other species were noted. Two cytotypes of Matricaria perforata were found among 23 seed sources collected throughout Canada. Eight Atlantic populations were diploid (2n=18) and 13 populations from the Prairies and East-central Canada were tetraploid (2n=36). One population from St. John's Newfoundland had anomalous chromosome counts of 2n=27, 36 and 37. In addition to the documentation of the present distribution of M. perforata, the extent of crossability was also investigated. Greenhouse experiments were conducted on the reproductive biology of 13 populations of M. perforata. The breeding system was found to be allogamous. Achene length and achene width were good taxonomic characters for differentiating the two cytotype races; however, the number of achenes per capitulum and achene weight were not. Twenty three Canadian populations of Matricaria perforata were grown in a common garden to examine the phenological and morphological differences. Diploid populations took a shorter period of time to bolt and flower, and exhibited less overwintering ability than the tetraploid populations. Consequently, diploid plants were predominantly annual and the tetraploid plants were biennial and perennial in growth form. Morphologically, the tetraploid plants were larger, more erect and more spreading in growth than the diploid plants. Life cycle effects on four populations were examined by monthly planting dates in the field. Plantings from May to late-July resulted in a lower percentage of plants bolting or flowering from each population. Plantings to the field after July did not flower, whereas plantings after September did not bolt or flower during the first growing season. No plants survived from the October planting date. A morphometric study was conducted on 14 populations of M. perforata collected in Alberta, Saskatchewan and Manitoba. Multivariate analyses were performed on 32 morphological characters and 13 environmental characters to determine if the sites were discriminating and if correlations could be made between the characters. Morphological differences were observed among the populations, but not correlated to the environmental characters. It was felt that these differences were not taxonomically meaningful since the main discriminating characters were vegetative and had a large amount of variability associated with them.