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Whitetop (Hoary Cress) (State designated weed)

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.

Status: State Designated Noxious Weed, Category 4. Widespread infestation. Control and maintenance of current weed infestations.

Control: Certain chemical controls can be effective. FCWP offers a 40 percent Cost Share on chemicals for controlling this species. Contact your local weed and pest office for further treatment recommendations.

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L.L. Berry, Bugwood.org