Phytogeography of Berkshire County, Massachusetts

Origin of the present vegetation of Berkshire County, Massachusetts, is discussed, with emphasis on glaciation, refugia of floristic elements during glaciation, migration patterns of taxa, and the effect these factors may have had on the present composition of the flora. The vegetation can be divided into five affinity groups: Eastern Deciduous Forest Region including a Southern and Midwestern sub-group, Alleghanian (Glaciated northeast and Appalachian Mountains), Boreal, Coastal Plain and Alien. Many taxa in the county are at or near their northern, southern, or eastern range limits. Selected state-listed rare taxa and common species are used to illustrate possible patterns of migration and limitations of distribution.