Centaurea is a genus of over 700 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.
Leuzea repens, synonyms including Acroptilon repens and Rhaponticum repens, with the common name Russian knapweed, is a bushy rhizomatous perennial, up to 80 cm 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 scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea. It is native to Europe and bears purple flower heads.
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.
Centaurea montana, the perennial cornflower, mountain cornflower, bachelor's button, montane knapweed or mountain bluet, is a species of flowering plant in the 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. This plant has become an invasive species in British Columbia, Canada. Centaurea montana grows in meadows and open woodland in the upper montane and sub-alpine zones, in basic areas. It grows to 30–70 centimetres (12–28 in) tall, and flowers mainly from May to August.
Bangasternus fausti is a species of true weevil known as the broad-nosed seed head weevil. It is used as an agent of biological pest control against noxious knapweeds, particularly spotted knapweed, squarrose knapweed, and diffuse knapweed.
Chaetorellia acrolophi is a species of tephritid fruit fly known as the knapweed peacock fly. It is used as an agent of biological pest control against noxious knapweeds, especially spotted knapweed.
Larinus minutus is a species of true weevil known as the lesser knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially diffuse knapweed and spotted knapweed.
Centaurea virgata is a species of Centaurea. It is native to Western Asia. The subspecies C. virgata subsp. squarrosa is known as squarrose knapweed.
Centaurea depressa, the low cornflower, is a species of Centaurea. It is native to southwestern and central Asia. Its common name is Iranian knapweed. The plant grows to 0.3 m (1 ft) tall and flowers from July to August. It can grow in nutritionally poor soil and is drought tolerant.
Succisa pratensis, also known as devil's-bit or devil's-bit scabious, is a flowering plant in the honeysuckle family Caprifoliaceae. It differs from other similar species in that it has four-lobed flowers, whereas small scabious and field scabious have five lobes and hence it has been placed in a separate genus in the same family. It also grows on damper ground.
Centaurea jacea, 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.
Centaurea nigra is a species of flowering plant in the family Asteraceae known by the common names lesser knapweed, common knapweed and black knapweed. A local vernacular name is hardheads.
Zygaena lonicerae, the narrow-bordered five-spot burnet, is a moth of the family Zygaenidae. The species was first described by Theodor Gottlieb von Scheven in 1777.
The aetherie fritillary is a butterfly in the family Nymphalidae.
Centaurea triumfettii, the squarrose knapweed, is a species of plant belonging to the genus Centaurea of the family Asteraceae.
Centaurea macrocephala is a species of flowering plant in the family Asteraceae, and a member of the thistle tribe, Cardueae (Cynareae). It has many common names, including bighead knapweed, big yellow centaurea, lemon fluff, yellow bachelor's button, yellow hardhat, and Armenian basketflower.
Centaurea stoebe, the spotted knapweed or panicled knapweed, is a species of Centaurea native to eastern Europe, although it has spread to North America, where it is considered an invasive species. It forms a tumbleweed, helping to increase the species' reach, and the seeds are also enabled by a feathery pappus.
Meadow knapweed is a fertile hybrid between black knapweed and brown knapweed. It is also known by the common names of hybrid knapweed or protean knapweed. The taxonomic status of the species is uncertain, and meadow knapweed has been variously described as different species. The Flora of North America refers to meadow knapweed as the nothospecies Centaurea × moncktonii.
