Tradescantia occidentalis (Spiderwort)
|Also known as:||Prairie Spiderwort, Western Spiderwort|
|Habitat:||part shade, sun; dry sandy soil; prairies, along roads, edges of woods|
|Bloom season:||May - September|
|Plant height:||10 to 24 inches|
|Wetland Indicator Status:||GP: UPL MW: UPL NCNE: UPL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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A raceme of up to 10 flowers at the top of the stem, and at the ends of branching arising from leaf axils; only 1 to a few open at a time. Flowers are 1 to 2 inches across, 3 round to egg-shaped petals with 6 bright yellow tipped stamens covered in long blue hairs in the lower half. Color ranges from blue to deep blue-violet and is occasionally pink or white. The flowers open in the morning and typically wilt by noon on hot days.
The 3 sepals and flower stalk are sparsely to densely covered in short glandular hairs, usually with a small tuft of non-glandular hairs at the tip. At the base of the flower cluster are 2 leaf-like bracts of unequal size, usually shorter and narrower than the leaves and folded lengthwise.
Leaves are narrow blades up to 15 inches long, to 1 inch wide, toothless and hairless, sheathing the stem. Each leaf is rather stiff, folded lengthwise with parallel veins. Stems are slender and smooth can have a bit of a zig-zag appearance due to the jointed leaf attachment. Plants are typically branched from leaf axils.
Fruit is rounded capsule containing up to 6 dark gray seeds. Seed is generally oval with a groove on one side and a hole on the other, the germ nestled inside. A pattern of ribs radiates from the center like the spokes of a wagon wheel.
There are 3 species of Spiderwort in Minnesota, all with similar flowers. Prairie Spiderwort is the most slender and spidery of the three, with stiffer leaves and bracts that are consistently folded up the middle. Long-bracted Spiderwort (Tradescantia bracteata) has longer and denser hairs on the bracts and flower stalks, bracts that are often wider and longer than the leaves, and is rarely branched. Ohio Spiderwort (Tradescantia ohiensis) has hairless sepals and relatively flat, floppy leaves. There are 2 varieties of T. occidentalis in the U.S., with var. occidentalis found in Minnesota; var. scopulorum is found in southwestern states.
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Photos by K. Chayka taken at Long Lake Regional Park, Ramsey County, and at Wild River State Park, Chisago County. Photos courtesy Peter M. Dziuk taken at Helen Allison SNA, Anoka County, and in Ramsey County.
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