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Noxious Weeds


Hoary cress or Whitetop (Cardaria draba (L.) Desv.) 

Mustard family (Brassicaceae)

 


GROWTH HABIT:
This deep rooted perennial native to Eurasia grows up to 2 feet tall (0.6 m) and grows commonly on disturbed sites with alkaline soils.
LEAVES: 
Theleaves are 1 to 1 1/2 inches (3 to 6 cm) long, are blue-green, waxy and lance-shaped. The lower leaves are stalked. The upper leaves are without stalks and have two lobes that clasp the stem
FLOWERS:
Flowerclusters with white flowers, each with four petals, give the plant a white, flat-topped appearance. Flowering occurs in spring.
SEEDS:Seeds are set by mid-summer. Heart-shaped seed capsules are produced and each contains two reddish-brown seeds separated by a narrow papery partition.
OTHER:
It is highly competitive with other species once it becomes established but can be controlled effectively with herbicides. Two other Cardaria species, lens-podded whitetop (C. chalepensis L.) and hairy whitetop (C. pubescens (C.A. Meg) Jarmolenko ) are common in the western U.S. Differences in seed capsules are used to identify each species. Hoary cress may grow from seed and also from root segments if the soil is tilled. Both seed and root pieces may be carried by equipment to infest new sites.
KEY CHARACTERS:
  • White flowers with four petals develop into bladder-like seed capsules in mid-summer.
DISTRIBUTION:Walker, Coleville - Mono County