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white top (Cardaria draba)
ODA rating: B
Other common names
hoary cress
Description
Perennial; blooms early May. Grows up to 2 ft tall. Deep-rooted. Lower leaves blue-green and lance shaped; upper leaves have two lobes clasping the stem. Many white flowers with four petals, giving plant a white, flat-topped appearance. Three known species, lens-podded, globe-podded, and heart-podded whitetop, identified by different shaped seed pods. Plants usually die back to roots in summer as seeds mature.
Impacts
Whitetop is a common weed species on alkaline soils, but is not restricted to them. It forms dense patches that can completely dominate sites, resticting the growth of other species or degrading pastures. The species is not toxic to livestock but neither is it grazed. Tens of thousands of acres are found in Oregon.
Click on image to view larger photo.
Image courtesy of Dan Sharratt, Oregon Dept. of Agriculture.
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Image courtesy of Lesley Richman, Burns BLM.
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Image courtesy of Bonnie Rasmussen, Oregon Dept. of Agriculture.
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Introduction
Native to southwest Asia. This invader is now distributed throughout the Pacific Northwest.
Distribution in Oregon
The first documented site of this plant in Oregon was 1909 in Union County
Map legend
Yellow: limited distribution
Red: abundant
Grey: not known to be present
Biological controls
No approved biocontrol agent is available.
Informational Links
WeedMapper
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