Comments: Berberis canadensis occurs in open woods, on bluffs and cliffs and along river banks in the eastern and central United States (Gleason and Cronquist 1991, Cook et al. 1987, Fernald 1970, Small 1933). Formerly an inhabitant of savannas and open woodlands, fire suppression has significantly restricted its habitat to sites with shallow soil (such as glades and cliffs) or areas with mowing or other canopy-clearing activities (such as powerline corridors, railroad/road right-of-ways and riverbanks).
The single extant population from Indiana is restricted to steep banks along the Tippecanoe River in the northern part of the state (Homoya 1992). Associated plant species include Besseya bullii, Lithospermum sp. and liverworts (Indiana Natural Heritage Data Center 1989). Prior to eradication efforts, Deam (1940) observed long stretches of the species along the banks of the Tippecanoe River, occupying an area "a few feet back from the edge of the bank and down the slope to high water mark".
Historically, B. canadensis occurred in Maryland in dry, calcareous woodlands, open fields and serpentine barrens (Maryland Natural Heritage Program 1992). No extant populations are known in the state.
In Missouri, B. canadensis is typically found on north-facing, rocky, wooded slopes; along streams; upper ledges or bluffs; exposed upper portions of bluffs on limestone, dolomite or sandstone; and mesic limestone/dolomite cliffs (Smith 1992, Roedner et al. 1978, Holt et al. 1974, University of Minnesota Herbarium (MIN)). Substrate composition usually consists of limestone, dolomite or sandstone with a somewhat basic pH (Smith 1993). Steyermark (1963) stated that the plant appears to be restricted to the edges of limestone bluffs where the soil is leached out, or near the contact point between chert or Roubidoux sandstone with limestone. Associated plant species in Missouri include Campanula rotundifolia, Carpinus caroliniana, Galium boreale ssp. septentrionale, Trautvetteria caroliniensis and Zigadenus elegans (Smith 1992, Steyermark 1963).
Berberis canadensis is found in 19 mountain counties in southwest Virginia (Huber 1993). Occupied habitat includes dry, open woodlands over limestone, dolomite, richer sandstone or shale substrates, rocky and cliffy areas and open areas and glades with naturally thin soil (Ludwig 1993, Ludwig 1992). Associated plant species in glades include Helianthus divaricatus, Juniperus virginiana and Schizachyrium scoparium. In rocky areas it is found with Cercis canadensis, Pellaea atropurpurea and Quercus muehlenbergii (Ludwig 1993).
Two historic populations are known from Georgia, but no recent efforts have been made to relocate them (Patrick 1989). Occupied habitat is described as dry, hard soil on upper, west-facing slopes and dry, rocky woods (Georgia Freshwater and Wetlands Heritage Inventory 1989).
In North Carolina, B. canadensis occurs in the Piedmont on mafic rocks (such as diabase, amphibolite and gabbro) and in the Blue Ridge on calcareous (limestone, dolomite, marble) and mafic rocks (amphibolite). It generally occurs in glade, open woodland, bluff or cliff situations (North Carolina Natural Heritage 1993, Weakley 1993, University of Minnesota Herbarium (MIN)). The species was historically found in fire-maintained habitats which kept the canopy open, but is now restricted to sites with very shallow soil or with mowing maintenance (right-of-ways, powerline corridors, etc.). Due to its association with mafic and calcareous rocks (uncommon to rare in the state), B. canadensis is often associated with other rare species. Typical associated plant species include Aquilegia canadensis, Cercis canadensis, Clematis ochroleuca, Desmodium spp., Echinacea laevigata, Matelea decipiens, Parthenium auriculatum, Pycnanthemum spp., Rhus aromatica, Silphium trifoliatum, Solidago rigida, Symphoricarpos orbiculatus and Viburnum rafinesquianum (North Carolina Natural Heritage 1993, Weakley 1993).
In Illinois, B. canadensis is known from a single extant site at the rim of a dry sandstone cliff (Illinois Natural Heritage Division 1992). No extant populations are known from the state (Schwegman 1989). Historic populations occurred on the rim of dry sandstone cliffs and in dry woodlands (Illinois Natural Heritage Division 1992, Mohlenbrock 1975).
No extant populations are known from Kentucky (Kentucky Natural Heritage Program 1993). Historic habitat is listed as limestone woodlands.
Berberis canadensis is known from Pennsylvania by one historic occurrence in the western portion of the state (Pennsylvania Natural Diversity Inventory-West 1993, Kunsman 1992). Habitat for the occurrence was listed as "woods and waste places around abandoned buildings" and "rocky woods" (Pennsylvania Natural Diversity Inventory-West 1993). There is some speculation whether the occurrence was native or was introduced to the site (Kunsman 1992).
Collections at the University of Tennessee-Knoxville Herbarium (TENN) suggest that occupied habitat is relatively open woodlands (Pyne 1994). Collections have been made from wooded slopes, shale slopes, bluffs, terraces along river bluffs and river banks.
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