Hoary Cress (White Top)

Hoary Cress (Whitetop)
Cardaria draba
Brassicaceae
(Mustard family)

Whitetop is common on alkaline, disturbed soils. It prospers in drought and is highly competitive with other species once it becomes established.

Growth Habit: Deep rooted perennial up to 2 feet tall, reproducing from root segments and seeds.

Leaves: Blue-green in color, lance-shaped. Lower leaves are stalked; upper leaves have two lobes clasping the stem.

Flowers: Plants have many white flowers with four petals, giving the plant a white, flat-topped appearance. Heart-shaped seed capsules contain two reddish-brown seeds separated by a narrow partition. Plants emerge in very early spring and have bloomed and set seed by mid-summer; prolific seed producer.

Roots: Whitetop reproduces perennially by its long taproot, by creeping rhizomes, and by broken root segments left in contact with the soil.

Other: Two other Cardaria species, lens-podded whitetop and hairy whitetop are common in the western U.S. with differences in seed capsules and fruit used to identify each species.