White Flowered Forbs

White Flowered Forbs
African rue
Broadleaved pepperweed
Field bindweed
Hary whitetop
Horehound
Lens-podded hoarycress
Onionweed
Oxeye daisy
Poison hemlock
White clover
White sweetclover
Whitetop

 

Hairy Whitetop
Cardaria pubescens (C. A. Mey) Jarmolenko (Mustard family, Brassicaceae)
 

Description

Multi-stemmed perennial forb, 18 to 20 inches tall; erect stems sparse to densely covered with simple short hairs; seed production is prolific; new shoots arise from buds on lateral roots or root fragments; establishes dense stands that exclude other vegetation.

Leaves: Gray-green, alternate, obovate, lanceolate, and oblong to elliptic; surfaces, especially lower, sparsely to densely covered with simple, short white hairs, margins irregularly toothed to entire; basal leaves short-stalked 3-1/2 inches long and 3/4 inch wide or less; sessile upper leaves are densely hairy with rounded to acute- lobed bases that clasp the stem.

Flowers: Flowers April to October; inflorescences often flat- topped; small (1/8 inch long), fragrant, white, 4-petaled flowers are numerous; sepals are covered with simple short hairs.

Fruits: Pods strongly inflated, spherical to ovoid in outline, 1/8 to 5/16 inch long and wide, covered with short hairs; style persistent, 1/16 to 1/8 inch long at the apex; seeds 1 to 2 per chamber, ovoid, slightly flattened, reddish-brown, less than 1/8 inch long and 1/16 inch wide.

Habitat

Cultivated and disturbed or degraded moist sites in meadows, grassland, chaparral, woodland, forest, and riparian communities, and roadsides; generally grows on alkaline to saline soils, but tolerates many soil types and moisture conditions within elevations that generally range from 3,000 to 8,000 feet.

Propagation/Phenology

Reproduces vegetatively from creeping roots and less importantly by seed; this species is an aggressive weed; mature plants develop extensive systems of persistent, deep vertical and horizontal roots to depths of 6-1/2 feet or more; root fragments generate new plants, but regeneration is poor in dry soils.

Comments

Native to central Asia; this species is difficult to distinguish from lens-podded hoarycress and whitetop in the seedling and vegetative states; hairy whitetop competes poorly with shrubs in natural communities. Arizona prohibited noxious weed and New Mexico Class A noxious weed.

Collage of images for Hairy whitetop

 

 
Forest Service Shield
Invasive plants and weeds of the national forests and grasslands in the southwestern region
Hairy whitetop clasping leaves and stem Hairy whitetop fruit Hairy whitetop flowers, clasping leaves, and stems Hairy whitetop plants