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Western Blue Flag

Western blue flag is a flower not a flag. It is the only species of Iris native to Alberta. It is widely distributed in the western United States but enters Canada only in Alberta where it is present along the southeastern side of the Rocky Mountains. Western blue flag is restricted to the Foothills Grassland and Parkland Subregions - areas that have been extensively changed by agriculture. There are few native occurrences in the province and the species is ranked S1 by the Alberta Natural Heritage Information Centre. Western blue flag is also designated as 'threatened' by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 1998).

In Alberta, western blue flag is restricted to the Foothills Fescue Grassland and Foothills Parkland Natural Subregions. The majority of native occurrences (distinct locations, where the species occurs) are in the Foothills Fescue Grassland and only one is in the Foothills Parkland, largely due to the climate of these regions. Ideal climates for growing western blue flag have been described as having cold, dry winters with moist springs and early summers followed by warm, dry, mid- to late summers.

Western blue flag is a member of the family Iridaceae . It is a perennial herb with thick (1 to 1.5 centimetres) rhizomes from which are produced tufts of leaves. The flowering stalks have two to four showy flowers that range in colour from pale blue to deep blue or lavender. White flowered forms also occur but are rare. The flowers bloom one after the other rather than all at once. Flowering dates for western blue flag throughout its range are May through July. In Alberta, flowering occurs between mid-June and early July.

To learn about other species at risk in Alberta click here.

Western Blue Flag

Western Blue Flag