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Western spiderwort was designated as Threatened by COSEWIC in
1992 and likewise under the Manitoba Endangered Species Act in
1994. It is a perennial with stout, fleshy roots, and flowers that
are generally blue or purple, but occasionally pink or white.
Flowers appear in late June to early July, and are pollinated by a
variety of insects, most commonly by sweat bees. In Manitoba, the
Western spiderwort grows on sandy soils, in open to partially
stabilized dune systems. The largest population of Western
spiderwort in Canada occurs in the Routledge Sandhills; a smaller
population is found in the Lauder Sandhills, northeast of Melita.
Threats include changes in land management practices,
especially burning and grazing regimes. Western spiderwort
requires open sand to thrive, and continued fire suppression
allows vegetation to encroach, stabilizing dune systems and
degrading spiderwort habitat. The continued spread of weedy
invasives, especially leafy spurge, is also a major concern for
the long-term health of Western spiderwort populations. Petroleum
exploration and all-terrain vehicle traffic in southwest Manitoba
pose significant threats to spiderwort habitat. An Ecologically
Significant Area protects part of the Routledge site, and a
portion of the Lauder site is owned by the Manitoba Habitat
Heritage Corporation, who purchased the site in order to conserve
habitat for this and other species.
For more information on the western spiderwort, please see the Conservation
Data Centre Field Guide or view the Manitoba's
Species at Risk brochure (PDF document, 210 KB).
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