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.
Rhaponticum repens, synonym Acroptilon repens, with the common name Russian knapweed, is a bushy rhizomatous perennial, up to 8 dm tall. Stems and leaves are finely arachnoid-tomentose becoming glabrous and green with age. The rosette leaves are oblanceolate, pinnately lobed to entire, 2–3 cm wide by 3–8 cm long. The lower cauline leaves are smaller, pinnately lobed; the upper leaves become much reduced, sessile, serrate to entire. The heads are numerous terminating the branches. Flowers are pink to purplish, the marginal ones not enlarged. The outer and middle involucral bracts are broad, striate, smooth with broadly rounded tips; the inner bracts are narrower with hairy tips. Pappus present with bristles 6–11 mm long. Fruit is a whitish, slightly ridged achene.
Centaurea cyanus, commonly known as cornflower or bachelor's button, is an annual flowering plant in the family Asteraceae native to Europe. In the past, it often grew as a weed in cornfields, hence its name. It is now endangered in its native habitat by agricultural intensification, particularly by over-use of herbicides. However, Centaurea cyanus is now also naturalised in many other parts of the world, including North America and parts of Australia through introduction as an ornamental plant in gardens and as a seed contaminant in crop seeds.
Centaurea scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea. It is native to Europe and bears purple flower heads.
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.
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.
Safranal is an organic compound isolated from saffron, the spice consisting of the stigmas of crocus flowers. It is the constituent primarily responsible for the aroma of saffron.
Centaurea montana, the perennial cornflower, mountain cornflower, bachelor's button, montane knapweed or mountain bluet, is a species of flowering plant in the daisy family Asteraceae, endemic to Europe. It is widespread and common in the more southerly mountain ranges of Europe, but is rarer in the north. It escapes from gardens readily, and has thereby become established in the British Isles, Scandinavia and North America.
Centaurea cineraria, the velvet centaurea, is – like some other plants – also known as dusty miller and silver dust. It is a small plant in the family Asteraceae and originates from the Island of Capraia in Italy, where it is called fiordaliso delle scogliere.
Centaurea iberica, the Iberian knapweed or Iberian star-thistle, is a species of Centaurea. It is native to southeastern Europe and southwestern Asia. It is known elsewhere as an introduced species and a noxious weed.
Centaurea jacea, the brown knapweed or brownray knapweed, is a species of herbaceous perennial plants in the genus Centaurea native to dry meadows and open woodland throughout Europe. It grows to 10–80 centimetres (4–31 in) tall, and flowers mainly from June to September.
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.
Centaurea nigra is a species of flowering plant in the daisy family known by the common names lesser knapweed, common knapweed and black knapweed. A local vernacular name is hardheads.
Jordanita chloros is a moth of the family Zygaenidae.
Coleophora conspicuella is a moth of the family Coleophoridae found in Asia and Europe. It was first described by Philipp Christoph Zeller in 1849.
Sierra de Santa Cruz is a mountain range in the Campo de Daroca comarca, Aragon, Spain. It is located north of the Laguna de Gallocanta.
Metzneria metzneriella is a moth of the family Gelechiidae. It is widely distributed throughout Europe, as well as Turkey and southern Siberia. The habitat consists of dry pastures and calcareous soils.
Eucosma hohenwartiana, the bright bell, is a species of moth of the family Tortricidae. It is found in China, Central Asia, North Africa and Europe, where it has been recorded from Sardinia, Sicily, Ireland, Great Britain, Spain, France, Germany, the Benelux, Denmark, Austria, Switzerland, Italy, the Czech Republic, Slovakia, Slovenia, Hungary, Poland, Romania, Bosnia and Herzegovina, Norway, Sweden, Finland, the Baltic region and Russia. The habitat consists of dry open areas and grassland.
Centaurea aspera, the rough star-thistle, is a species of Centaurea found in Europe and in New York, United States.
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.
