Centaurea solstitialis (yellow starthistle) is a bushy winter annual (family Asteraceae) from the Mediterranean region in Europe that has invaded over 12 million acres in California. Yellow starthistle inhabits open hills, grasslands, open woodlands, fields, roadsides, and rangelands, and it is considered one of the most serious rangeland weeds in the state. It propagates rapidly […]

Chondrilla juncea (rush skeletonweed) is a perennial or biennial forb (family Asteraceae) and can be found scattered throughout California but is considered an uncommon weed. It can grow in disturbed soils of roadsides, croplands, especially irrigated grain fields, semi-arid pastures, rangelands, and residential properties. Plants are highly competitive for water and nutrients. It is native […]

Glebionis coronaria (crown daisy) is a flowering annual (family Asteraceae) found along the central and south coast of California. Crown daisy commonly invades riparian areas, coastal dunes, prairies and scrub. It is a common ornamental plant that escapes garden settings and easily invades disturbed areas. The seeds of crown daisies sprout very quickly after rain, […]

Cirsium arvense (Canada thistle) is a perennial (family Asteraceae) found scattered throughout California, except in the Sonoran and Mojave Deserts and the southern Sierra Nevada. Canada thistle forms dense patches which may crowd out native vegetation. This clump-forming plant reproduces by seed and vegetatively from its extensive root system. Control is difficult because root fragments […]

Cirsium vulgare (bull thistle) is a perennial or biennial forb (family Asteraceae) Bull thistle is widespread in California and is most common in coastal grasslands, along edges of fresh and brackish marshes, and in meadows and mesic forest openings in the mountains below 7,000 feet (2,120 m). It is most troublesome in recently or repeatedly […]

Atriplex semibaccata (Australian saltbush) is a low-statured, spreading, shrubby perennial (family Chenopodiaceae) that is native to Australia. It is distinguished by its small, grey-green leaves that are white on the underside and red, diamond-shaped fleshy fruits. Australian saltbush was introduced as a forage plant in the 1920’s. Since then, it has escaped cultivation and is […]

Asphodelus fistulosus (onion weed) is an annual/perennial herb (family Liliaceae) found in dry, sandy and rocky places, as well as pastures, roadsides and waste places. Livestock avoid eating it, allowing it to create dense stands that crowd out more desirable forage species in pastures. It is primarily found along coastal regions of Southern California. It […]

Asparagus asparagoides (bridal creeper or African Asparagus fern) is a rhizomatous perennial herb (family Liliaceae) found in riparian woodlands of California’s central and south coast. Asparagus asparagoides colonizes both disturbed areas and undisturbed native habitats, but its current distribution is very limited. Plant shoots can form dense mats that limit light levels and then die […]

Arundo donax (giant reed) is a tall perennial grass (family Poaceae) that typically forms dense stands on disturbed sites, sand dunes, riparian areas, and wetlands. It has invaded central and coastal Southern California river valleys, central California river valleys in San Luis Obispo and Monterey counties, the San Francisco Bay Area, the Sacramento and San […]

Agrostis stolonifera (creeping bentgrass) is a perennial grass (family Poaceae) and is located throughout California. Creeping bentgrass is an escaped turfgrass that can aggressively out-compete native grass species by forming dense mats.