|Title||The vascular plants of Emmet and Cheboygan Counties, Michigan: patterns and problems in geographic affinities|
|Year of Publication||1954|
|Degree||Doctor of Philosophy|
|Number of Pages||280 pp.|
|University||University of Michigan|
|City||Ann Arbor, MI|
The present study treats the vascular plants of a limited area in northern Michigan from two standpoints: floristic and phytogeographic. The first consideration has been to prepare, on the basis of field and herbarium studies, an accurate list of the flora of the area, for no phytogeographic study can be more accurate than the taxonomy which underlies it. The second has been the geographic analysis of this flora, drawing on relevant material from glacial geology and other related fields. A thorough evaluation of published accounts and herbarium material, supplemented by nine seasons of personal collecting, has resulted in records, supported by authentic specimens examined, for 1159 species of vascular plants from the area composing Emmet and Cheboygan counties, at the northern end of the Lower Peninsula of Michigan. Of these, one-fourth (295) are not considered to be indigenous in the region. The North American ranges of the 866 indigenous species in the flora have been mapped, and the species grouped into a number of floristic elements, based on their present ranges. The basic unit mapped has been the species, including all infraspecific taxa, since in many cases it appears quite possible that the latter have been postglacial in origin. In some cases, addition of closely related species gave more meaningful maps. This method of mapping, on a floristic basis alone, all the species of a flora has been described by Cain who termed it "the most staisfactory one yet devised" for classifying the floristic elements of a local area. Present range, at least, is a criterion which can be applied more or less uniformly to an entire flora. In the present instance, several subdivisions are recognized under six major types of distribution patterns. It is not claimed that these groups are of equivalent rank or importance from any particular point of view. They happen to be the groups into which the species of our flora can be placed with the fewest ambiguities, and some of them have considerably more meaning than others.