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COSEWIC Assessment and Status Report on the Eastern Flowering Dogwood in Canada

Distribution

Global Range

This is a species of eastern North America, ranging from southern Michigan, southern Ontario and eastward to southern Maine in the north and south to eastern Texas and to northern Florida. It is common in the deciduous forests of the middle and southern states, occurring from the coast to high in the Allegheny Mountains in the south. Two well separated populations occur in the mountains of north-eastern and central-eastern Mexico (Figure 2).


Figure 2: Global Distribution of Cornus florida

Figure 2: Global distribution of Cornus florida (after Little, 1971).

After Little, 1971.


Canadian Range

In Canada this species is limited to the Carolinian Zone (Deciduous Forest Region) of southern Ontario. It ranges from just west of Toronto in Oakville, along or near the Niagara Escarpment through Halton and Hamilton regions to several sites in the Niagara Region and south-westward. It is especially abundant on the sand plain of Norfolk County with outlying populations in Brant (historical), Middlesex, Elgin, and Lambton counties, and another cluster of sites in Chatham-Kent and Essex County. This species continues to have some occurrence in all the historical regions (Fox & Soper, 1952), but not extending to Brant County. The extent of occurrence (EO) is estimated to approximate the area of the Carolinian Zone (22 500 km2), based on its distribution shown in Figure 3. The area of occupancy (AO) is estimated as 1 km2per site (based on personal observation). With 154 sites documented between 1975 and 2005 this totals about 150 km2, considering some overlap of grids. The dots of Figure 3 are based on a comprehensive list of precise locations compiled from herbarium records, Natural Heritage Information Centre records and recent field observations.


Figure 3: Total Native Distribution of Cornus florida in Canada

Figure 3: Total native distribution of Cornus florida in Canada.