Diffuse knapweed (Centaurea diffusa)
Diffuse knapweed (Centaurea diffusa)
Diffuse knapweed (Centaurea diffusa)
Diffuse knapweed (Centaurea diffusa)

Other common names
White knapweed, Spreading knapweed, Tumble knapweed

Description
Biennial, flowers midsummer to fall. Grows to 3 feet tall. Single-stemmed plant with numerous lateral branches. Flowers are white to rose, sometimes purplish. Flower heads are slender with pointed, fringed bracts. Spreads by seed, aided by the tumbling of windblown mature plants.

Impacts
Will form dense stands on any...

Dodder (Cuscuta)
Dodder (Cuscuta)
Dodder (Cuscuta)

Other common names
Beggarweed, Strangle tare, Scaldweed, Devil's guts, Strangleweed, Hairweed, Goldthread, Witches' shoelaces, Hailplant, Love vine, Angel's hair, Pull down, Hell bind, Tangle gut

Description
Annual, parasitic plant that lacks chlorophyll; flowers July to October. Stems are yellowish, thread-like and twining. Leaves are reduced to thread-like scales. Flowers are white to pink, numerous, shallow-cupped, and...

Dyer's woad (Isatis tinctoria)
Dyer's woad (Isatis tinctoria)
Dyer's woad (Isatis tinctoria)
Dyer's woad (Isatis tinctoria)

Other common names
Asp of Jerusalem

Description
Perennial or biennial that grows up to three feet tall. It has multiple stems that arise from the base. Foliage has a distinctive blue-green cast with a whitish glaze. The upper leaves are smaller and clasp the stem with ear-like projections. Flowers are bright yellow, small and in clusters. Flowers have four spoon-shaped petals. Fruits pods are flat and black or purplish-brown....

English ivy (Hedera helix)
English ivy (Hedera helix)
English ivy (Hedera helix)

Other common names
Common ivy, Branching ivy, Glacier ivy, Needlepoint ivy, Sweetheart ivy, Ivy

Description
Perennial, flowers when light and nutrients are optimum. Woody, evergreen vine with long, trailing stems. Leaves alternate, are waxy. Juvenile leaves are lobed, mature leaves are larger and pointed with no lobes. Green or white flowers produce black berries.

Impacts
Rapid and massive growth of...

Eurasian watermilfoil (Myriophyllum spicatum)
Eurasian watermilfoil (Myriophyllum spicatum)
Eurasian watermilfoil (Myriophyllum spicatum)
Eurasian watermilfoil (Myriophyllum spicatum)

Description
Perennial, aquatic plant. Purplish-red, branching stems grow up to five feet long. Feather-like leaves in whorls of four at each node. Male flowers are purplish and appear at the end of the flowering stem. Lower, whitish flowers are female.

Impacts
Eurasian watermilfoil has significant economic impacts to waterways, irrigation ditches and drainage canals, where it can inhibit flow and increase maintenance costs. It is...

European water chestnut (Trapa natans)
European water chestnut (Trapa natans)
European water chestnut (Trapa natans)
European water chestnut (Trapa natans)

Other common names
Singhara ling, Bullnut

Description
Annual, aquatic plant. Upper floating leaves are diamond-shaped with toothed edges, on inflated, spongy stalks, in clusters up to 20 inches across. Submersed leaves are long and narrow, or often replaced with green, feather-like structures. Flowers are small, solitary and white to light-purple. Fruit is a large swollen nut with two to four sharp spines.

Impacts...

False brome (Brachypodium sylvaticum)
False brome (Brachypodium sylvaticum)
False brome (Brachypodium sylvaticum)

Other common names
Slender false brome

Description
Perennial grass. Forms short, squatty bunches. Stems are hollow with broad, flat, one-quarter to one-third inch wide lax leaves and a leaf sheath open to the base. Leaf color is a bright green that often remains through fall and part of winter. Leaf margins and lower stems are hairy; ligules are membranous. Flowers are born in a true spike that droops noticeably, and have spikelets...

Field bindweed (Convolvulus arvensis)
Field bindweed (Convolvulus arvensis)
Field bindweed (Convolvulus arvensis)
Field bindweed (Convolvulus arvensis)

Other common names
Morning glory

Description
Perennial, blooms June to September. Stems are prostrate, one to four feet long, from an extensive root system that often climbs or forms dense tangled mats. Leaves alternate and are arrowhead-shaped with lobes at the base. Flowers are bell- or trumpet-shaped, white to pinkish and one inch in diameter. Fruit is a small, round capsule, usually four-seeded.

Impacts...

Flowering rush (Butomus umbellatus)
Flowering rush (Butomus umbellatus)
Flowering rush (Butomus umbellatus)
Flowering rush (Butomus umbellatus)

Other common names
Grassy rush, Water gladiolus

Description
Perennial, aquatic plant in the family Butomaceae; not a true rush species. Distinctive and easy to identify when flowering, difficult when not in flower. It is a tall plant growing to a height of 1.5 meters in marshes and in aquatic habitats. The plant crown is topped by an umbel of showy white or pink flowers emerging in late summer to early fall. The flowers consist of...

French broom (Genista monspessulanas)
French broom (Genista monspessulanas)
French broom (Genista monspessulanas)

Description
Perennial, blooms April to June. Grows three to ten feet tall. Evergreen shrub is similar to Scotch broom, except that plants do not grow as erect, leaves are retained the entire year, leaves are trifoliate and more numerous, and yellow flowers are smaller.

Impacts
This plant, an aggressive pioneer species, takes advantage of land disturbances to establish and spread. In California, large infestations displace native...