Descurainia sophia (Herb Sophia)
|Also known as:||Flixweed|
|Life cycle:||annual, biennial|
|Habitat:||part shade, sun; disturbed soils, waste areas, roadsides, railroads, agricultural fields|
|Bloom season:||May - July|
|Plant height:||10 to 30 inches|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Elongating racemes 2 to 12 inches long of stalked flowers at the tips of branching stems, with a small, flattish cluster of flowers blooming at the tip and fruit forming below. Flowers are up to 1/8 inch long with 4 mostly erect yellow petals and 4 erect to ascending, linear-oblong, greenish-yellow sepals that are about as long as or slightly longer than the petals. In the center is a slender style surrounded by 6 yellow stamens longer than the sepals. Stalks are very slender, erect to ascending, and up to about ½ inch long. Sepals and flower stalks are hairless or sparsely covered in non-glandular hairs.
Leaves and stems:
Leaves are 2 or 3 times pinnately compound, broadly lance-oblong in outline, basal and the lowest leaves stalked, up to 6 inches long and 2½ inches wide, feathery with numerous, deeply to shallowly lobed divisions, becoming smaller, stalkless, and less lobed as they ascend the stem. Surfaces and stalks are variably covered in branched or star-shaped, non-glandular hairs. Basal leaves wither by flowering time.
Flower stalks become ascending to widely spreading in fruit. Fruit is a straight to slightly curved, erect to ascending pod called a silique, up to about 1 inch long, longer than the stalk at maturity, slender and not noticeably plumper than the stalk. Inside is a single row of 12 to 25 seeds, with barely visible constrictions between the seeds.
Herb Sophia is a weed of roadsides, gravel pits and agricultural fields and was once upon a time considered a noxious weed in Minnesota, but Round-up Ready crops took care of that, so it is no longer considered much of a pest. It closely resembles the native Tansy Mustard (Descurainia pinnata), which is typically glandular hairy and has fruits that are shorter than the stalk and obviously plumper than the stalk. Herb Sophia is likely under-reported in Minnesota.
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Photos by K. Chayka taken in Ramsey County. Photos courtesy Peter M. Dziuk taken in Lac Qui Parle, Marshall, Otter Tail, Polk and Pope counties.
Have you seen this plant in Minnesota, or have any other comments about it?