An invasive species is an introduced organism that negatively alters its new environment. Although their spread can have beneficial aspects, invasive species adversely affect the invaded habitats and bioregions, causing ecological, environmental, and/or economic damage. Sometimes the term is used for native species that invade human habitats and become invasive pests. In the 21st century they have become a serious economic, social, and environmental threat.
Centaurea is a genus of between 350 and 600 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich. In the western United States, yellow starthistles are an invasive species. Around the year 1850, seeds from the plant had arrived to the state of California. It is believed that those seeds came from South America.
Biological control or biocontrol is a method of controlling pests such as insects, mites, weeds and plant diseases using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role. It can be an important component of integrated pest management (IPM) programs.
Onopordum acanthium is a flowering plant in the family Asteraceae. It is native to Europe and Western Asia from the Iberian Peninsula east to Kazakhstan, and north to central Scandinavia, and widely naturalised elsewhere, with especially large populations present in the United States and Australia. It is a vigorous biennial plant with coarse, spiny leaves and conspicuous spiny-winged stems.
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial or detrimental effects on the target organisms and the community. Allelochemicals are a subset of secondary metabolites, which are not required for metabolism of the allelopathic organism. Allelochemicals with negative allelopathic effects are an important part of plant defense against herbivory.
Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a member of the genus Centaurea in the family Asteraceae. This species is common throughout western North America but is not actually native to the North American continent, but to the eastern Mediterranean.
Cirsium arvense is a perennial species of flowering plant in the family Asteraceae, native throughout Europe and western Asia, northern Africa and widely introduced elsewhere. The standard English name in its native area is creeping thistle. It is also commonly known as Canada thistle and field thistle.
Centaurea calcitrapa is a species of flowering plant known by several common names, including red star-thistle and purple starthistle. It is native to Europe but is rarely found there, it is known across the globe as an introduced species and often a noxious weed. The species name calcitrapa comes from the word caltrop, a type of weapon covered in sharp spikes.
Silybum marianum has other common names including cardus marianus, milk thistle, blessed milkthistle, Marian thistle, Mary thistle, Saint Mary's thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle. This species is an annual or biennial plant of the family Asteraceae. This fairly typical thistle has red to purple flowers and shiny pale green leaves with white veins. Originally a native of Southern Europe through to Asia, it is now found throughout the world.
Centaurea solstitialis, the yellow star-thistle, is a member of the family Asteraceae, native to the Mediterranean Basin region. The plant is also known as golden starthistle, yellow cockspur and St. Barnaby's thistle The plant is a thorny winter annual species in the knapweed genus.
Carduus pycnocephalus, with common names including Italian thistle, Italian plumeless thistle, and Plymouth thistle, is a species of thistle. It is native to: the Mediterranean region in southern Europe, North Africa, and Western Asia; East Europe and the Caucasus; and the Indian Subcontinent.
Centaurea melitensis is an annual plant of the Asteraceae, 1 to 11 decimetres high, with resin-dotted leaves and spine-tipped phyllaries. This plant is native to the Mediterranean region of Europe and Africa. It was introduced to North America in the 18th century; the first documented occurrence in California is in the adobe of a building constructed in San Fernando in 1797. It is also naturalized on a number of Pacific islands.
8-Hydroxyquinoline is a chelating agent which has been used for the quantitative determination of metal ions.
The Blue Oak Ranch Reserve, a unit of the University of California Natural Reserve System, is an ecological reserve and biological field station in Santa Clara County, California. It is located on 3,260 acres (13.2 km2) in the Diablo Range, northwest of Mount Hamilton, at 1,500 ft (460 m) elevation.
Puccinia jaceae var. solstitialis is a species of fungus in the Pucciniaceae family. It is a plant pathogen that causes rust. Native to Eurasia, it is the first fungal pathogen approved in the United States as a biological control agent to curb the growth of the invasive weed yellow starthistle.
Chaetorellia succinea is a species of tephritid fruit fly that was accidentally released in 1991 into the United States and had since become one of the major biological pest controls against the noxious weed yellow starthistle.
Dr. Ragan (Ray) Callaway is a prominent plant and community ecologist that obtained his Masters of Science at the University of Tennessee in 1983 and his Doctor of Philosophy at the University of California, Santa Barbara in 1990 [1]. Currently, he researches and teaches out of the University of Montana in Missoula, Montana, USA [1]. His research concentrates on the interactions within plant communities and ecosystems, predominantly those in alpine environments [1].
Centaurea stoebe, the spotted knapweed or panicled knapweed, is a species of Centaurea native to eastern Europe. It is also an invasive species in the United States, and particularly widespread in dryer regions of the West, which has a similarly dry climate as the Mediterranean. This species along with Centaurea diffusa are a tumbleweed—breaking off at the top of the roots which facilitates the dispersal of its seeds.
Nigropallidal encephalomalacia or Chewing disease is a neurological condition that affects horses that have eaten certain toxic plants. Affected animals are unable to prehend food because of lip and tongue paralysis, and may appear to keep their jaws open with the tongue protruded because of reduced jaw tone. Some horses may appear to show their upper teeth because of increased hypertonicity of the facial and upper lip muscles. Other animals may show severe depression and carrying their heads low. Because poisoned horses are unable to eat, these animals become weakened and ultimately die of starvation.
