Shinnersoseris rostrata (Annual Skeletonweed)
|Also known as:
|sun; dry prairie, sand dunes and blowouts
|July - August
|4 to 16 inches
|Wetland Indicator Status:
|MN county distribution (click map to enlarge):
|National distribution (click map to enlarge):
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Branching clusters of stalked flowers. Flowers are about 1/3 to ½ inch across with 6 to 11 petals that are mostly ascending and do not spread fully open. Petal color is lavender to light pink, with white tips. At the base of a petal is a slender, dark purple column with a protruding style that has a split tip.
Leaves and stems:
Leaves are linear, up to 6 inches long and ¼ inch wide, toothless, hairless, stalkless, and spreading to drooping, the uppermost leaves reduced to bracts. Attachment is typically opposite in the lower plant and alternate above, the lower leaves withering away by flowering time, leaves farther up withering away later. Stems are green, hairless, and much branched.
Formerly known as Lygodesmia rostrata, Annual Skeletonweed is at the eastern fringe of its range in Minnesota. According to the DNR, in MN it's restricted to unstable sand dunes and blowouts where there is little competition, and movement of the sand aids seed stratification and germination. It was listed as a Threatened species in 1984. The only natural populations are believed to be in Polk and Norman counties, with other locations likely planted in restoration projects. It resembles the related and more common Skeletonweed (Lygodesmia juncea), which is also found on dry, sandy prairie, but has larger, (usually) 5-petaled flowers and much smaller leaves that persist through fruiting.
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Photos courtesy Peter M. Dziuk taken in Norman County.
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