Cardaria draba, Hoary Cress

Gardens & Landscapes, Invasive Species, Extension Master Gardener December 16, 2015 Print Friendly and PDF

Invasive Species: Cardaria draba, Hoary Cress

Hoary cress, or whitetop, is an invasive perennial forb in the mustard family that can grow up to 2 ft. (0.6 m) tall. The leaves are soft, gray-green, 1.5 to 3 in. (3.7 to 7.6 cm) long with fine hairs and heart-shaped bases. The lower leaves tend to have more hairs than the upper leaves. The upper leaves clasp to the stem of the plant. Flowering occurs in early spring to early summer when white four-petaled flowers develop in clusters at the apex of the stem. The fruit are heart-shaped seed pods. Hoary cress invades rangelands, pastures, stream banks, and open forests primarily in the western United States, although it does occur in the East. It can form large infestations that can displace native species and reduce grazing quality. Hoary cress is native to Central Europe and Western Asia and was first introduced into the United States in the early 20th century.

What are invasive species and why should we be concerned about them? 


Taxonomy: Scientific and Common Names for This Species

Capparales > Brassicaceae > Cardaria draba (L.) Desv

Synonym(s): whitetop, globed-podded hoarycress, peppergrass, whiteweed

Cardaria draba - USDA PLANTS Profile

Distribution Maps

Hoary cress - The reported distribution of this invasive species across the United States. (Source: Invasive Plant Atlas of the United States)

Up-to-the-minute distribution maps and why they are important

Reporting This Invasive Species

What is the best way and place to report the occurrence of an invasive species? 

 How to report an invasive species sighting to EDDMapS - Early Detection & Distribution Mapping System

EDDMapS - Report an invasive species to EDDMapS

Cooperative Extension Offices - Find your local Cooperative Extension office on this map provided by USDA

 

How to Identify

This invasive species can be identified by looking for the characteristics described in the paragraphs that follow.

Plant

 An invasive perennial forb in the mustard family that can grow up to 2 ft. (0.6 m) tall.

hoary cress hoary cress
Barry Rice, sarracenia.com, bugwood.org Steve Dewey, Utah State University, bugwood.org

Foliage

The leaves are soft, gray-green, 1.5 to 3 in. (3.7 to 7.6 cm) long with fine hairs and heart-shaped bases. The lower leaves tend to have more hairs than the upper leaves. The upper leaves clasp to the stem of the plant.

hoary cress hoary cress
Pedro Tenorio-Lezama, bugwood.org Pedro Tenorio-Lezama, bugwood.org

Flower

Flowering occurs in early spring to early summer when white four-petaled flowers develop in clusters at the apex of the stem.

hoary cress

hoary cress

Steve Dewey, Utah State University,
bugwood.org

Barry Rice, sarracenia.com, bugwood.org

Fruit

The fruit are heart-shaped seed pods.

hoary cress hoary cress
Joseph M. DiTomaso, University of California - Davis, bugwood.org Julia Scher, USDA APHIS PPQ, bugwood.org

Native Species That Resemble Hoary Cress

 

Oxypolis filiformis, water cowbane - Images at invasive.org

water cowbane water cowbane
Karan A. Rawlins, University of Georgia, bugwood.org Karan A. Rawlins, University of Georgia, bugwood.org

 

Oxypolis fendleri, Fendler's cowbane - Images at invasive.org

Fendler's cowbane Fendler's cowbane
Dave Powell, USDA Forest Service, bugwood.org Mary Ellen (Mel) Harte, bugwood.org

 

Additional Images for Hoary Cress

 

Hoary cress - Images at Invasive.org

 

Learning Resources for Hoary Cress

 

Additional Information, Biology, Control and Management Resources

Control and management recommendations vary according to individual circumstances. Location, habitat, weather, and a variety of other conditions are factors that help determine the best treatment choice. To find the safest and most effective treatment for your situation, consult your state's land-grant institution. If you will use chemicals as part of the control process, always refer to the product label.

United States Land-Grant University System - Find your land-grant university's College of Agriculture, Cooperative Extension Service, or other related partner on this map provided by USDA.

Element Stewardship Abstract - The Nature Conservancy

Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS

Weed of the Week - USDA Forest Service

Cardaria draba - Missouri Plants

Jepson Herbarium - University of California

Plant Profile - Cal-IPC

Invasive Plant Management - Cal-IPC


 

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.