Phenological data in this study were collected between 1949 and 1980. Data were recorded on field trips with classes or while doing vegetation research in various plant communities, or from herbarium speciments or from dated slides. With some exceptions, which are noted, the records are mostly from central Minnesota. All records, for each species, include date, phenophase and location. The records have been obtained from several hundred locations. Some locations may have been visited only once. Some like the Cold Spring Heron Colony, the Waubun Prairie, the Partch Woods and others used for class field trips, or special research, were visited many times for many years.
Partch, Max, "Plant Phenology in Central Minnesota" (1999). Biology Faculty Publications. 1.