Hoary cress, also known as white top, is a perennial forb in the mustard family native to Eurasian.  Leaves are alternate, 1.6-4 in long, blue green, and lance-shaped. Grows erect from 10 to 18 inches high.  Roots are rhizomatous and usually occur at depth of 29-32 inches.  The root system of hoary cress consists of vertical and lateral roots from which new rosettes and flowering shoots arise.  Seed capsules are heart shaped, and contain two reddish-brown seeds (source).

It is a priority invasive species in the tallgrass prairie ecoregion in Nebraska.

Hoary cress is generally considered unpalatable to livestock and spreads as a result.  It is a highly competitive weed once it becomes established. Hoary cress spreads primarily by extremely persistent roots and will eventually eliminate desirable vegetation and become a monoculture displacing native vegetation.