ARS | Publication request: TALL WHITETOP (LEPIDIUM LATIFOLIUM)

Submitted to: Government Publication/Report
Publication Type: Research Notes
Publication Acceptance Date: September 22, 2004
Publication Date: October 8, 2005
Citation: Young, J.A., Blank, R.R., Clements, C.D. 2005. Tall whitetop (lepidium latifolium). Bureau Land Management Resource Note No. 76.

Technical Abstract: Tall whitetop (Lepidium latifolium) is native to eastern Europe and adjacent Asia. In the San Luis Valley of Colorado everyone refers to the plant as iron weed. Throughout much of the western United States it is known as tall whitetop. Unfortunately, there is another weed commonly called 'whitetop' that is widely distributed on rangelands. The scientific name of this whitetop is Cardaria draba [L.] Desv. and the accepted common name is hoary cress. This may appear quite confusing, but it results in more of a communication rather than an identification problem. Both of the weeds known as whitetop are members of the Brassicaceae or mustard family. They both have the typical four-parted mustard flower with white petals. Both species have vigorous creeping roots. These roots have buds that can produce either shoots or roots and both species form colonies. With all these shared characteristics it would appear that tall whitetop and whitetop are very difficult to distinguish. The adjective 'tall' is the key. Whitetop (hoary cress) can color entire meadows with a dazzling display of white flowers, but a month later the leaves dry on the fragile 1 to 1.5 foot tall stems and the plants virtually disappear. Tall whitetop (perennial pepperweed) plants can easily reach heights of 6 feet or more and the stems are semi-woody at the base. Tall whitetop forms thickets that are visible at all seasons of the year and the dead plant material persist for several years.