Hollister Field Office
Print Page

Hoary Cress (Cardaria draba)

Mustard Family (Brassicaceae)


Cardaria draba (hoary cress).  Photo courtesy of Barry Rice, Bugwood.org
Photo: Barry Rice, Bugwood.org

       Cardaria draba (hoary cress). Photo courtesy of Steve Dewey, Utah State University, Bugwood.org      
Photo: Steve Dewey, Utah State University, Bugwood.org

Cardaria draba (hoary cress).  Photo courtesy of Chris Evans, River to River CWMA, Bugwood.org
Photo: Chris Evans, River to River CWMA, Bugwood.org

Description/Habitat:  A stout, erect perennial, native to Central Europe and Western Asia, hoary cress (Cardaria draba) can grow up to 0.5 meters tall. Soils with neutral to alkaline pH and disturbed sites, including excessively grazed areas, are prime areas for hoary cress. It can be found in a variety of non-shaded habitats such as fields, meadows, pastures, open grasslands, waste areas, roadsides, gardens, feedlots, watercourses, along irrigation ditches, and at the edge of riparian habitats.
Roots/Reproduction:  The root system consist of deeply penetrating vertical and lateral root segments with thick, corky bark, large energy reserves, and numerous underground buds. These buds are where the rhizomes and new aboveground shoots arise. Reproduction occurs from seeds or from the underground rhizomes.
Leaves:  The arrowhead shaped leaves are grayish-green in color, covered with fine hairs and feel soft to the touch. Basal leaves form a rosette in early spring and tend to be more slender but larger than stem leaves, and narrow into a short petiole. Leaves on the upper portion of the plant clasp the stem.
Flowers:  Flower pedicels (stalks) diverge slightly from the stem and are white with four petals about 2.5 millimeters long, clumped at the top of the stem and are flat in appearance.
Seeds:  Each of the seedpods are heart shaped and contain one or two oval reddish-brown seeds.
Flowering Period:  March – June (sometimes as early as December)
Management:  On Fort Ord National Monument, hoary cress is known to occur in a single location, but it remains top priority to prevent the spread of the species to other areas of the property. The rhizomatous nature of the plant creates management problems, limiting the effectiveness of manual treatment methods. Because of this, management of hoary cress requires two stages. The flower heads are removed to prevent seed production, and the remaining plant structures are sprayed with a glyphosate herbicide. Although glyphosate herbicides are not considered the most effective method for treating Hoary cress, we have successfully reduced the number of plants growing each year, possibly because treatment was started while this population was still small. Monitoring and follow up will be required until we are sure we have completely controlled this species.

"Invasive Plants, NA - Forest Health Protection." Northeastern Area State & Private Forestry - USDA Forest Service. United States Forest Service. Web. 20 Dec. 2011. <http://na.fs.fed.us/fhp/invasive_plants/weeds/>.
"Cal-IPC: Cardaria draba." Cal-IPC: California Invasive Plant Council Home. California Invasive Plant Council. Web. 20 Dec. 2011. <http://www.cal-ipc.org/ip/management/plant_profiles/Cardaria_draba.php>.
"Hoary Cress, Cardaria draba (Capparales: Brassicaceae)." Invasive Species: Information, Images, Videos, Distribution Maps. Center for Invasive Species and Ecosystem Health. Web. 20 Dec. 2011. <http://www.invasive.org/browse/subthumb.cfm?sub=5232>.

Last updated: 08-20-2012