Draba arabisans (Rock Whitlow-grass)
|Also known as:||Arabian Whitlow-grass|
|Habitat:||shade, sun; cliffs, rocks, rock outcrops|
|Bloom season:||May - June|
|Plant height:||4 to 16 inches|
|Wetland Indicator Status:||none|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Elongating clusters of stalked flowers at the top of the stem and the ends of branching stems in the upper plant. Flowers are 1/8 to ¼ inch across with 4 white petals notched at the tip and 6 pale yellow stamens in the center. Buds are yellowish. The sepals behind the flower are hairy and egg-shaped to oblong.
Leaves and stems:
Leaves are up to 2½ inches long, to 1/3 inch wide, stalkless, the basal leaves mostly narrowly spatula-shaped, the upper becoming smaller and mostly oblong. Leaf surfaces are covered in star-shaped hairs; leaf edges may be toothless but more often have a few sharp teeth especially at the tip end. Stems are single or multiple from the base, freely branched, and sparsely covered in star-shaped hairs.
Fruit is a pod up to ½ inch long, held erect to slightly spreading, narrowly oblong with a pointed tip, usually twisted into a spiral, on stalks up to about 1/3 inch long. The pods dry to a yellow or tan color.
A rare species not only in Minnesota, but throughout its range, Rock Whitlow-grass can be found only on a few cliff locations in Minnesota, primarily along the north shore of Lake Superior and along the Canadian border, but with a few disjunct populations in Olmsted and Fillmore counties. According to the DNR, it was listed as a Special Concern species in 1984 (they have some nice images of the fruits on their species page). When going in search of this plant, we knew the locations would be difficult to get to, but got lucky when we found a plant on a small shelf of a cliff, near enough to the bottom so we could easily see it, but not quite close enough to easily reach it. Standing on a rock, hanging onto the shelf with one hand, holding the camera above it with the other and shooting like mad hoping to get something in focus, we did manage to get a few worthy images before we lost our hold on the rock and had to give up.
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Photos courtesy Peter M. Dziuk taken in Olmsted County.
Have you seen this plant in Minnesota, or have any other comments about it?