Western Blue Flag
Last Update/Review: June 17, 2002
Status | Description | Reproduction | Habitat | Human Use | Limiting Factors | Management and Outlook
Status
Western blue flag occurs in the Foothills Grassland Natural Region, an area stretching from the western edge of the Milk River Ridge to the foothills west of Carway and north to Okotoks, Alberta. Of the 750 km² portion of the Foothills Grassland Natural Region in which western blue flag may have occurred prior to European settlement, less than 100 square km remains in an uncultivated condition. Only a small fraction of the natural habitats in the Natural Region are suitable for western blue flag.
Surveys in the late 1980s in this area found only six populations of western blue flag, with a total of fewer than 7500 stems. Since then, a seventh population has been identified, and total numbers are now estimated at 7800 stems. Two sites near Carway and one at Whiskey Gap have significant populations. Two more sites have very small populations. These sites are all on private property and have no legal protection. The sixth site has some protection because of its location in Police Outpost Provincial Park. In addition, western blue flag has disappeared from at least two sites where it once occurred.
Western blue flag occurs at the northern edge of its range in southwestern Alberta, in a narrow band, 27 km by 10 km, paralleling the international border. It is considered rare in Alberta. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has designated the western blue flag as threatened in Canada. Alberta contains the only known populations of this species in Canada.
Western blue flag commonly occurs from Montana south to Mexico, and although it is abundant in portions of the Rocky Mountain states and Great Plains, there are large areas of its range where it is very localized. It occurs on moist meadows and streambanks that are wet early in the spring but are often dry later in the summer.
Description
The western blue flag (Iris missouriensis) is a member of the Iris Family or Iridaceae. The origin of the name is Greek; golden-winged Iris was the Greek goddess of the rainbow, and a messenger of Hera, queen of the gods.
The
flowers usually occur two (up to four) to a stem. Each pale blue or
blue-violet flower has nine petal-like segments in the form of three
sepals, three petals and three enlarged styles. There are purple veins
radiating from a bearded yellow spot on each of the outer segments
(sepals) which are spreading and often recurved and are 4 to 6 cm long.
The inner segments (petals) are erect or arch upward. The styles curve
down over the sepals. The white-flowered form is golden-throated with
little or no veining. The seed capsule is oblong, about 2-5 cm long.
When mature it splits along three sides to release dark brown seeds.
The plant is 30-60 cm tall, with pale blue-green leaves 10-40 cm long and 5-10 mm wide. The leaves grow from the base of the plant and are folded in half lengthwise. The flowering stems are leafless or may have one leaf. The previous year's leaves are persistent. The roots grow from a thickened, dark-coloured rhizome (rootstock).
Reproduction
Western blue flag is a long-lived perennial with a thick underground rhizome that enables populations to maintain themselves over long periods of time. The rootstock allows the plant to withstand heavy trampling and to spread rapidly when competition from other plants is reduced.
The flowers, which are produced only in the most favourable conditions of reduced competition and sufficient water, are cross-pollinated by insects, usually bees. The seeds are released when the capsule opens and is shaken by the wind or passing animals. The seeds fall close to the plant where the habitat is likely to be suitable for germination and growth.
Habitat
Most of the sites suitable for western blue flag are on level or slightly sloping ground where there is abundant subsurface moisture.
Western
blue flag occurs at the edges of wet meadows or seepage springs, where
the soil is damp in the spring but well drained and drier by midsummer.
Stands are often found close to willow thickets around moist depressions
or along minor drainages. Western blue flag prefers full sun. The habitat
range suitable for western blue flag lies within a narrow region of
moist meadows in a transition zone between drier upland slopes supporting
shrubby cinquefoil and rough fescue (Potentilla fruticosa/Festuca
scabrella), and wet areas dominated by tufted hair grass (Deschampsia
cespitosa). Other plants often associated with western blue flag
include sedges (Carex spp.), northern reed grass (Calamagrostis
inexpansa), wild chives (Allium schoenoprasum), silverweed
(Potentilla anserina), and heart-leaved Alexanders (Zizia
aptera).
Human Use
Irises have been valued throughout the ages. They have been used as symbols of royalty, the three parts of the flower representing wisdom, faith and courage. The Alberta Native Plant Council, a conservation group dedicated to protecting our native vegetation, has chosen the western blue flag as its emblem, and as a symbol of Alberta's rare and native plants. Dramatic and vulnerable, flowers like the western blue flag are valued by photographers and educators who wish to promote the protection of native plants. Western blue flag has been used medicinally by aboriginal people; the rootstock was added to a smoking mixture to induce nausea or chewed raw to relieve toothaches. Research is now being conducted on western blue flag to investigate its possible antiviral and anticancer properties.
Limiting Factors
The main factors limiting the occurrence of the western blue flag are its very specific habitat requirements and the loss of this habitat. Western blue flag grows in a narrow band between permanent wetlands and dry uplands, where the soil is damp but well drained in the spring, and dry later in the summer. It will grow neither in the drier prairie areas, nor in wetter zones near ponds and creeks. This narrow band of habitat may be altered by natural processes and can also be easily damaged by human activities such as drainage, overgrazing and cultivation.
The foothills grassland environment in southwestern Alberta has been subject to extensive cultivation and conversion to tame pasture. Approximately 60% of the overall landscape in the vicinity of western blue flag populations has been so altered. Moist meadow habitats have been modified more extensively than the drier uplands with the result that western blue flag is confined to a very small number of sites. Of the nine recorded sites in southern Alberta, two have been destroyed by human action.
In dry years, normally moist sites can be cultivated, replacing the natural vegetation (including western blue flag) with hay or cereal crops. The Police Outpost Provincial Park population had been limited in size by the conversion of surrounding fields to tame pasture.
Water in natural drainage systems is often diverted into dugouts, depriving wet meadows of moisture. One Carway site has recently had a new cattle-watering dugout constructed within a western blue flag meadow. This may decrease the amount of suitable moist meadow habitat. The Whiskey Gap site is in extremely poor condition, probably due to alterations in the drainage from heavy use by cattle.
Normally western blue flag appears to benefit from moderate grazing, as cattle generally avoid this unpalatable plant and graze surrounding plants, which reduces competition. The major site near Carway has light to moderate grazing and a large and healthy western blue flag population. The Police Outpost Provincial Park population is ungrazed and very few flowers are produced, possibly due to competition from surrounding vegetation. However, since Alberta is at the northern limit of the western blue flag's range, when water is a limiting factor overgrazing may further deteriorate the site. For example, at the Whiskey Gap site, which is both dry and overgrazed, western blue flag did not bloom for 25 years, finally flowering in the wet spring of 1991.
Several other factors may influence the viability of western blue flag populations in Alberta. In areas subject to high levels of recreation use (such as Police Outpost Provincial Park) trampling and picking could damage local populations. Shade, caused by willows invading open wet meadow margins, may also decrease habitat suitability. Even more serious is the threat posed by agricultural herbicides. Western blue flag is not likely to survive in areas where glyphosate (100% effective at killing western blue flag) or 2,4-D (90% to 100% effective) are used for range management.
Management and Outlook
The management and protection of rare plants is a new and challenging area of conservation in Alberta. At present, this province has no legislation which specifically protects plants. This responsibility is spread among several provincial government departments, including Alberta Sustainable Resource Development and Alberta Community Development.
Western
blue flag was designated as a threatened species by the Committee on
the Status of Endangered Wildlife in Canada in 1990. In anticipation
of this status, the World Wildlife Fund (Canada) and Alberta Forestry,
Lands and Wildlife (now Alberta Sustainable Resource Development) joined
forces to prepare a Provincial Management Plan for this species. This
plan was drafted in the same format as the management plans being prepared
for other threatened species of wildlife. General goals are proposed
regarding minimum population size land use and site protection guidelines,
the distribution of information and educational material, and possible
legislative and management approaches. The implementation of this plan
will require a unique partnership of government agencies, nongovernment
groups and private landowners.
The various levels of government can act in several different ways. Lands can be protected by purchasing them or initiating conservancy agreements with private landowners. Rare and/or significant habitats (including rare plants) are criteria that can be used to evaluate lands proposed for acquisition or agreements. Landowners interested in long-term protection can arrange conservancy agreements to protect blue flag sites and their water sources.
Alberta Community Development administers the Historical Resources Act under which a natural site of scientific interest may be designated, thus protecting it as an historic resource. This can include sites supporting rare or otherwise significant plants or plant communities.
At a municipal level, the western blue flag sites have been indentified as "Environmentally Significant Areas" (ESAs). Municipal governments can act to control conflicting land uses that are under their jurisdiction.
Landowners can also help to ensure a secure future for this species in Alberta. Moderate grazing seems to sustain the populations as long as the groundwater levels are maintained. Landowners with western blue flag can help by ensuring water levels in small creeks and meadows are maintained in natural condition. Drought, of course, will cause fluctuations, but human- or cattle-caused diversions near western blue flag sites can and should be avoided. Most importantly, these sites should not be cultivated or treated with herbicides. Careful management and use of native prairie protects not only the western blue flag, but a multitude of rare and wonderful plants, birds, mammals and insects. If we leave them in their natural sites, protect the water and surrounding vegetation, this beautiful and threatened species will survive and thrive for future generations to enjoy.
Further information on western blue flag can be found in:
| Moss, EH. 1959. Flora of Alberta. University of Toronto Press, Toronto. Revised by J. G. Packer (1983). |
Wallis, C. and C. Bradley, 1989. Status Report on Western Blue Flag (Iris missouriensis Nutt,) an Endangered Species in Canada Committee on the Status of Endangered Wildlife in Canada. |
| Or contact: | |
| Wildlife Management Branch Fish and Wildlife Division Alberta Sustainable Resource Development 9915 -108 Street Edmonton, Alberta T5K 2G8 |
Curator of Botany Provincial Museum of Alberta 12845 -102 Avenue Edmonton, Alberta T5N OM6 |
