Portuguese broom (Cytisus striatus)
Portuguese broom (Cytisus striatus)
Portuguese broom (Cytisus striatus)
Portuguese broom (Cytisus striatus)

Other common names
Striated broom, Hairy-fruited broom

Description
Perennial, blooms April to June. Grows 3 to 10 feet tall. Evergreen shrub is similar to Scotch broom, except pods are inflated and hairy all over, giving the appearance of pussy willow buds. Stems are more silvery, but difficult to distinguish until leaves and flowers fall off.

Impacts
Portuguese broom is similar to Scotch broom in...

Puncturevine (Tribulus terrestris)
Puncturevine (Tribulus terrestris)
Puncturevine (Tribulus terrestris)
Puncturevine (Tribulus terrestris)

Other common names
Goat’s head, Bullhead, Mexican sandbur, Texas sandbur

Description
Annual, blooms July to October. Grows prostrate to the ground from a taproot and forms dense mats four feet across. The plant produces numerous stems, some growing up to six feet long. Leaves are opposite, hairy, and divided into four to eight pairs of leaflets, each about 1/2-inch long. Flowers are small, yellow, 1/2-inch wide, with five...

Purple loosestrife (Lythrum salicaria)
Purple loosestrife (Lythrum salicaria)
Purple loosestrife (Lythrum salicaria)
Purple loosestrife (Lythrum salicaria)

Other common names
Purple lythrum

Description
Perennial, blooms midsummer. Grows up to 7 feet tall. Upright, bushy plant. Flowers are pink to purple, possessing five to six petals on a long spike. Spreads by seed and spreading rhizomes that form dense, woody mats.

Impacts
Its showy purple flowers crown a vigorous plant that crowds out marsh vegetation required by wildlife for food and shelter....

Purple nutsedge (Cyperus rotundus)
Purple nutsedge (Cyperus rotundus)
Purple nutsedge (Cyperus rotundus)
Purple nutsedge (Cyperus rotundus)

Description
Perennial, grows 1 to 2 feet high. Stems are three-cornered and generally longer than the basal leaves. Leaves are grass-like, 1/8 to 1/3 inch wide and 2 to 6 inches long. Inflorescence consists of numerous purple spikelets. Underground tubers are oblong, covered by persistent reddish scales, and often formed in chains.

Impacts
Purple nutsedge is considered one of the world's top 10 agricultural weeds. It thrives in...

Purple starthistle (Centaurea calcitrapa)
Purple starthistle (Centaurea calcitrapa)
Purple starthistle (Centaurea calcitrapa)
Purple starthistle (Centaurea calcitrapa)

Other common names
Red starthistle

Description
Annual or biennial. Rosettes form in May and June; blooms midsummer through fall. Grows 1 to 6 feet tall. Plant is covered in fine hairs. Leaves are divided into narrow linear segments. Rosettes have spines in the center. Flower heads are purple with straw-colored, spine-like bracts over 1 inch in length. Seeds are not plumed, which is the distinguishing factor between this plant and...

Ragweed (Ambrosia artemisiifolia)
Ragweed (Ambrosia artemisiifolia)
Ragweed (Ambrosia artemisiifolia)
Ragweed (Ambrosia artemisiifolia)

Description
Annual, blooms in the late summer. Grows to 4 feet tall. Stems and leaves are blue-green and covered with fine hairs. Leaves are divided, and the bottom sides are covered in fine hairs, giving a gray appearance. Flowers are inconspicuous and found on terminal branches.

Impacts
This plant is common throughout the West and causes hay fever in many people. It is commonly found along ditches and waste areas. It is not highly...

Rush skeletonweed (Chondrilla juncea)
Rush skeletonweed (Chondrilla juncea)
Rush skeletonweed (Chondrilla juncea)
Rush skeletonweed (Chondrilla juncea)

Description
Perennial, blooms July to September. Grows 1 to 4 feet tall. Yellow flowers are 3/4 inch in diameter with 7 to 15 petals. There are coarse, down-bent hairs on the lower 4 to 6 inches of stem; it has almost no leaves. Spreads primarily by seed, but roots scattered by cultivation can aid in spread.

Impacts
An aggressive plant in both rangeland and cropland, particularly in light-textured soil. It has been the target of...

Russian knapweed (Acroptilon repens)
Russian knapweed (Acroptilon repens)
Russian knapweed (Acroptilon repens)
Russian knapweed (Acroptilon repens)

Other common names
Turkistan thistle, Creeping knapweed, Mountain bluet, Russian cornflower, Hardheads

Description
Perennial, blooms summer to fall. Grows up to 4 feet tall. Forms dense colonies with stems that are erect and branched. Lower leaves are deeply lobed, 2 to 4 inches long; upper leaves are entire or serrate. Cone-shaped flowering heads are 1/4 to 1/2 inch wide with one flower, pink to lavender, growing at each branchlet...

Saltcedar (Tamarix ramosissima)
Saltcedar (Tamarix ramosissima)
Saltcedar (Tamarix ramosissima)
Saltcedar (Tamarix ramosissima)

Description
Perennial shrub, blooms April to October. Grows 5 to 20 feet tall. Bark on saplings and stems is reddish-brown. Leaves are small and scale-like on highly branched, slender stems. Flowers are pink to white, and 5-petaled.

Impacts
Saltcedar is an escaped ornamental and has become naturalized along streams, canals, and reservoirs in much of the arid West. Dense stands form adjacent to springs and waterways, robbing native...

Saltmeadow cordgrass (Spartina patens)
Saltmeadow cordgrass (Spartina patens)
Saltmeadow cordgrass (Spartina patens)
Saltmeadow cordgrass (Spartina patens)

Other common names
Salt marsh cordgrass

Description
A rhizomatous perennial grass that is 1 to 4 feet tall with very narrow leaf blades 0.5 to 2 mm wide. The leaves and flowering stems are deciduous, being replaced each year. Leaf color is light green, often in contrast to the colors of native tufted hairgrass and sedges. The dark-colored flowering panicles are not taller than the leaves. Infestations grow slowly outward, forming...