Small-flowered sand-verbena COSEWIC assessment and status report: chapter 4

Distribution

Global range

Small-flowered sand-verbena is a species of western North America (Figure 3). In Canada, it is distributed in widely scattered localities from southeastern Alberta, as well as at one southwestern Saskatchewan locality. In the United States, small-flowered sand-verbena is distributed in eastern Montana, Nebraska, Wyoming, Utah, Colorado, Nevada, eastern California, northern Arizona, New Mexico, North Dakota, South Dakota, western Kansas and northern Texas.

Figure 3. North American distribution of small-flowered sand-verbena.

Figure 3. North American distribution of small-flowered sand-verbena.

Canadian range

In Canada, the species is restricted to southeastern Alberta (6 sites) and southwestern Saskatchewan (one site near the Alberta border) (Figure 4). Small-flowered sand-verbena is considered rare in Canada and in Alberta and Saskatchewan.

Figure 4. Canadian distribution of small-flowered sand-verbena. Alberta: 1) Lost River; 2) Purple Springs; 3) Wolf Island; 4) Bow Island; 5) Bull Pound, South Saskatchewan River; 6) Suffield National Wildlife Area. Saskatchewan: 7) South Saskatchewan River, east of Alberta border

Figure 4. Canadian distribution of small-flowered sand-verbena.

Alberta

Small-flowered sand-verbena has been found in southeastern Alberta at six locations; namely, Lost River, Bow Island, Purple Springs, Bull Pound, Suffield National Wildlife Area, and Wolf Island. These sites all occur within an area northeast of Bow Island (at the confluence of the Bow, Oldman and South Saskatchewan Rivers), west to the Saskatchewan border and south to the Montana border at widely scattered localities. Small-flowered sand-verbena is always associated with a river system. Five of the sites are associated with the South Saskatchewan River. One site is associated with the Lost River near the border with Montana. Historically, small-flowered sand-verbena has been located near Milk River (1895) by John Macoun.

Saskatchewan

In Saskatchewan the species occurs only at one site just east of the Alberta border, south of Empress, Alberta where the South Saskatchewan River bends into Saskatchewan and out again to join the Red Deer River (Hudson 1982).

Small-flowered sand-verbena may not now occur at the previously known sites in Canada. In the past ten years, the species has only been found at the Bow Island and Suffield National Wildlife Area sites. Small-flowered sand-verbena may be present in the seed bank at its other locations.

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