Centaurea

Source: Wikipedia, the free encyclopedia.
"Basket flower" redirects here. For the unrelated Australian plant, see Adenanthos obovatus.

Centaurea
Centaurea pullata
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Carduoideae
Tribe: Cardueae
Subtribe: Centaureinae
Genus: Centaurea
L.
Type species
Centaurea centaurium
L.
Diversity
Over 700 species
Synonyms
List
  • Acosta DC.
  • × Acostitrapa Rauschert
  • Acrocentron Cass.
  • Acrolophus Cass.
  • Alophium Cass.
  • Ammocyanus (Boiss.) Dostál
  • Antaurea Neck.
  • Behen Hill
  • Benedicta Bernh.
  • Calcitrapa Heist. ex Fabr.
  • Calcitrapoides Fabr.
  • Carbeni Adans.
  • Carbenia Adans.
  • Cardosanctus Bubani
  • Cestrinus Cass.
  • Chartolepis Cass.
  • Cheirolepis Boiss.
  • Chrysopappus Takht.
  • Cistrum Hill
  • Cnicus L.
  • × Colycea Fern.Casas & Susanna
  • × Colymbacosta Rauschert
  • Colymbada Hill
  • Crepula Hill
  • Cyanus Mill.
  • Cynaroides (Boiss. ex Walp.) Dostál
  • Eremopappus Takht.
  • Erinacella (Rech.f.) Dostál
  • Eriopha Hill
  • Grossheimia Sosn. & Takht.
  • Heraclea Hill
  • Hierapicra Kuntze
  • Hippophaestum Gray
  • Hookia Neck.
  • Hyalea Jaub. & Spach
  • Hymenocentron Cass.
  • Jacea Mill.
  • × Jaceacosta Rauschert
  • × Jaceitrapa Rauschert
  • Lepteranthus Neck. ex Fourr.
  • Leucacantha Nieuwl. & Lunell
  • Leucantha Gray
  • Lopholoma Cass.
  • Melanoloma Cass.
  • Menomphalus Pomel
  • Mesocentron Cass.
  • Microlophus Cass.
  • Paraphysis (DC.) Dostál
  • Pectinastrum Cass.
  • Petrodavisia Holub
  • Phaeopappus (DC.) Boiss.
  • Phalolepis Cass.
  • Philostizus Cass.
  • Phrygia (Pers.) Bosc
  • Piptoceras Cass.
  • Platylophus Cass.
  • Plumosipappus Czerep.
  • Podia Neck.
  • Polyacantha Gray
  • Psora Hill
  • Pterolophus Cass.
  • Pycnocomus Hill
  • Rhacoma Adans.
  • Sagmen Hill.
  • Seridia Juss.
  • Setachna Dulac
  • Solstitiaria Hill
  • Sphaerocephala Hill
  • Spilacron Cass.
  • Staebe Hill
  • Stenolophus Cass.
  • Stephanochilus Coss. ex Maire
  • Tetramorphaea DC.
  • Tomanthea DC.
  • Triplocentron Cass.
  • Veltis Adans.
  • Verutina Cass.
  • Wagenitzia Dostál

Centaurea (/ˌsɛntɔːˈriːə/)[1] 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.

Common names

Common names for this genus are centaury, centory, starthistles, knapweeds, centaureas and the more ambiguous "bluets"; a vernacular name used for these plants in parts of England is "loggerheads" (

common knapweed). The Plectocephalus group – possibly a distinct genus – is known as basketflowers. "Cornflower" is used for a few species, but that term more often specifically means either C. cyanus (the annual cornflower) or Centaurea montana (the perennial cornflower). The common name "centaury" is sometimes used, although this also refers to the unrelated plant genus Centaurium.[2]

The name is said to be in reference to Chiron, the centaur of Greek mythology who discovered medicinal uses of a plant eventually called "centaury".[3]

Description

Knapweeds are robust

arid regions, have a long and strong taproot
.

Common knapweed (C. nigra
), perhaps the single most abundant Centaurea species of England
C. bella
)
endemic
to Turkey

Ecology

Certain knapweeds have a tendency to dominate large stretches of landscape together with a few other plants, typically one or two grasses and as many other large herbaceous plants. The

red fescue
(Festuca rubra) in addition to cock's-foot and false oat-grass.

Due to their habit of dominating ecosystems under good conditions, many Centaurea species can become

Controlled burning may also be used, though the timing is important to avoid the plants having seeded already, and neither allowing sufficient time for them to regrow from the rootstock.[5]

Yet other species of Centaurea – mostly ones that occur between Italy and the

extinct, while the western Caucasus endemics C. leptophylla and C. straminicephala are at least very rare and C. hedgei and C. pecho from the same region are certainly not abundant either. The last four species would be adversely affected by the proposed Yusufeli Dam, which might actually destroy enough habitat
to push the two rarer ones over the brink of extinction.

brown knapweed
(C. jacea).

Centaurea are copious

endangered Karner blue (Plebejus melissa samuelis) which visits introduced spotted knapweed – and day-flying moths – typically Zygaenidae, such as Zygaena loti or the six-spot burnet (Z. filipendulae). The larvae of some other Lepidoptera
species use Centaurea species as food plants; see List of Lepidoptera that feed on Centaurea. Several of these are used in biological control of invasive knapweeds and starthistles.

Knapweed root weevil
(Cyphocleonus achates) larvae bore into the roots of spotted and to a lesser extentely diffuse knapweed, sometimes killing off the entire plant.

Also used in biological control are

cornflower
(C. cyanus) as larval food; later generations switch to yellow starthistle. The flies are generally considered less efficient in destroying the growing seedheads than the weevils, but may be superior under certain conditions; employing flies and weevils in combination is expensive and does not noticeably increase their effect.

Use by humans

Although the genus may be considered by a quite significant number of relatively informed individuals to have an overall negative impact on human interests, particularly agricultural interests, the situation is not straightforward enough to simply declare the genus, or, at least, its most aggressively-spreading species, altogether negative. For instance, due to their moderate to high nectar production, which can occur over a comparatively long duration, many species of Centaurea are popular food sources for

cornflower (C. cyanus) in a European setting, to grow adjacent to fields. Although they support and attract many types of beneficial life (not just beetles), these areas are known as beetle banks. When they are present, some pests may be drawn away from crops to them and predatory insects and arachnids that feed upon pest insects will be better-supported by these more naturalized areas. They additionally have the beneficial aspect of supporting pollinators, unlike many field crops such as maize. Moreover, being untreated with pesticides and providing more diversity
, plants growing in more wild areas adjacent to farms produce more insects that attract and support birds which can also feed on pests that would harm crops. Insect production is especially high for beetle banks that have enough plants that serve in the role of host plant for immature insects, rather than just in the roles of adult food and/or shelter provision.

Some plants which are considered invasive or problematic in certain areas can have beneficial qualities that outweigh their negative qualities from a human and/or human agricultural point of view, although this sometimes requires some human management – particularly if adequate biological control has not been established for the more aggressive species. An example is wild parsnip,

predators can help to keep overall pest populations low.[8]

invasive weed that yields a fine honey

The abundant

common knapweed (C. nigra) and globe knapweed (C. macrocephala
) are locally important pollen sources for honeybees in mid-late summer.

coevolved with the knapweed and are little harmed if at all, aided by native microorganisms that break down or even feed on the abundantly secreted compound.[4]
Thus, 8-hydroxyquinoline is potentially useful to control American plants that have become invasive weeds in the diffuse knapweed's native range.

Arctiin from C. imperialis kills cancer cells in culture

Arctiin, found in C. imperialis, has shown

School of Pharmacy, University of London) "the antioxidant activity [...] of the young whorls of Centaurea calcitrapa, both in the DPPH and in the lipid peroxidation inhibition assays, [is] very interesting and [the] species should be investigated phytochemically and biochemically focusing on these properties". Extracts from C. calcitrapa were furthermore found to have significant xanthine oxidase (XO)-inhibiting activity.[9]

Spotted knapweed as well as other species are rich in

amaro. In western Crete, Greece a local variety[verification needed] of C. calcitrapa called gourounaki (γουρουνάκι "little pig") also has its leaves eaten boiled by the locals. In the same island an endemic local species, C. idaea called katsoula (κατσούλα), tsita (τσίτα) or aspragatha (ασπραγκάθα), has its leaves eaten boiled by the locals too.[10]

Cornflower
blue
#6495ED

Some species are cultivated as

area denial weapon is probably in some way connected with C. calcitrapa and its spiny seeds. This plant is attested to by the colloquial name "caltrop" at a time when the weapons were still called by their Roman name tribulus.[11] Lastly, the color cornflower blue
is named after C. cyanus. Cornflower is also used as a cut flower.

Systematics and taxonomy

Centaurea horrida

As namesake member of the

monotypic Cnicus seems in fact to properly belong in Centaurea.[12]

Research in the late 20th century shows that Centaurea as traditionally defined is

polyphyletic. A number of 19th- and 20th-century efforts to reorganize the genus were not successful, and it is not yet clear what the consequences of the recent research will be for classification of this genus and other related genera. The type species C. centaurium stands somewhat apart from the main lineage of knapweeds and thus the taxonomic consequences of a rearrangement might be severe, with hundreds of species needing to be moved to new genera. It has thus been proposed to change the type species to one of the main lineages to avoid this problem. What seems certain however is that the basketflowers – presently treated as a section Plectocephalus – will be reinstated as a distinct genus in the near future. The rock-centauries (Cheirolophus), formerly usually included in Centaurea, are now already treated as separate genus.[2]

Species

Main article: List of Centaurea species

Better-known Centaurea species include:

Formerly placed here

Plant species placed in Centaurea in former times include:

  • Acroptilon repens
     – Russian knapweed (as C. repens)
  • Cheirolophus crassifolius – Maltese rock-centaury (as C. crassifolia, C. spathulata)
  • Femeniasia balearica
     (as C. balearica)
  • Volutaria muricata (as C. muricata)

Footnotes

  1. ^ Sunset Western Garden Book, 1995:606–607
  2. ^ a b Keil (2006), Keil & Ochsmann (2006).
  3. OCLC 61461560
    .
  4. ^ a b Hierro & Callaway (2003), Vivanco et al. (2004).
  5. ^ a b Emery & Gross (2005).
  6. ^
    PMID 27341588
    .
  7. ^ a b "Which flowers are the best source of nectar?". Conservation Grade. 2014-10-15. Archived from the original on 2019-12-14. Retrieved 2017-10-18.
  8. ^ Wäckers et al. (2005)
  9. ^ Pieroni et al. (2002).
  10. ^ Stavridakis (2006)
  11. puncture vine
    , later named Tribulus terrestris.
  12. ^ Panero & Funk (2002), Keil (2006), Keil & Ochsmann (2006).
  13. ^ AMEA Botanika İnstitutunun əməkdaşları Azərbaycan florasında yeni növ aşkarlayıblar. science.gov.az
  14. ^ Centaurea tymphaea Plants of the World Online

References

Further reading

External links
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