Grand coulee owl-clover (Orthocarpus barbatus) COSEWIC assessment and status report: chapter 6

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Distribution

• Global range
• Canadian range

Global range

Orthocarpus barbatus occurs east of the Cascade Mountains in western North America, from the southern Okanagan Valley in south-central British Columbia south to Grant County in south-central Washington (Figure 2, Hitchcock et al. 1959, Pojar 2000, Douglas et al. 2002).

Figure 2. Distribution of Orthocarpus barbatus in North America.

Canadian range

In British Columbia, Orthocarpus barbatus is known from four extant occurrences in the southern Okanagan Valley and the southern Similkameen Valley. All of the sites are within a 2.5 by 16 km band along the United States border (Figure 3). The first collection of this species in British Columbia was recorded by G.W. Douglas in 1994 (Douglas et al. 1998a, 1998b) at “Veronica Lake”^Footnote 5. The fourth, and most discovered in 2003 by J. Fenneman in the Kilapoola Lake area in South Okanagan Grasslands Protected Area.

The writers searched a number of apparently suitable habitats throughout the southern Okanagan Valley in 2003 and found no further populations. Other botanists (e.g., F. Lomer, pers. comm., 2003; M. Martin, pers. comm., 2003) have also searched the southern Similkameen and southern Okanagan valleys from 1996 to the present without success. The area (ca. 45 km²) supporting Orthocarpusbarbatus was not visited by botanists until the early 1990s thus it is not surprising that this species was only recently discovered. Approximately 70% of the potential habitat area (Figure 3) has been searched to date.

Figure 3. Range and potential habitat of Orthocarpus barbatus in the southern Okanagan and Similkameen valleys of British Columbia.

Orthocarpus barbatus is just one of a number of species recently discovered (since the 1980s) along the British Columbia border from the Princeton area to the Roosville area. Some of these species include: Antennaria flagellaris, Carex vallicola, Collomia tenellus, Floerkea proserpinacoides, Hedeoma hispida, Lipocarpha micrantha, Orobanche ludoviciana, Phacelia ramosissima, Psilocarphus brevissimus, Silene spaldingii and Trichostema oblongum (Douglas et al. 1998a, 1998b). Most of these species have at least one thing in common; the areas in which they were found were never subjected to botanical collecting. Examination of collection localities in all major herbaria in Canada reveal that none of the many active field botanists working along the border ever collected in the immediate vicinity of the recently collected plants.