Hoary Cress AKA Whitetop (Lepidium draba)
Noxious Under Alberta's Weed Control Act
Submitted By Kelly Cooley, CoolPro Solutions
Hoary Cress is a troublesome and persistent non-native invasive plant that grows well in our area crops, rangeland, or areas of soil disturbance. An unpalatable member of the Mustard Family, in late April Hoary Cress sends up inconspicuous grey-green shoots & leaves from its creeping perennial root system established in previous years. Plants reach bud stage in early to mid-May, and flower before June. These small four-petalled flowers are bright white and arranged in clusters at the tops of the stems, leading to the common name of Whitetop. In early June these flowers mature to seeds which drop through the rest of the year. Seeds may germinate the following season, or lay idle and viable for decades afterward, waiting for soil disturbance to allow them to sprout a new patch. More information can be found in the Hoary Cress fact sheet from the Alberta Invasive Species Council, and you can report this invader yourself using their free EDDMapS application on your mobile device. For local control options for Hoary Cress please contact our Agricultural Fieldman at 403-339-8741.