Centaurea depressa (Centaurea)

Overview

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A: Fruit; B: embryo in situ; C: transection of fruit of <i>Centaurea depressa</i>

Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in English:

Centaurea, Iranian Knapweed, Low Cornflower

Common Names in Informal Latinized N:

Centaurea

Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Genus Centaurea

Annuals , biennials, or perennials, 20-300 cm, glabrous or tomentose . Stems erect , ascending , or spreading , simple or branched. Leaves basal and cauline; petiolate or sessile; proximal blade margins often ± deeply lobed , (spiny in C. benedicta ), distal ± smaller, often entire, faces glabrous or ± tomentose, sometimes also villous , strigose , or puberulent , often glandular-punctate. Heads discoid , disciform , or radiant, borne singly or in corymbiform arrays. Involucres cylindric or ovoid to hemispheric . Phyllaries many in 6-many series, unequal, proximal part appressed , body margins entire. distal parts expanded into erect to spreading, usually ± dentate or fringed , linear to ovate appendages , spine. tipped or spineless. Receptacles flat, epaleate, bristly . Florets 10-many; outer usually sterile , corollas slender and inconspicuous to much expanded, ± bilateral ; inner fertile , corollas white to blue, pink, purple, or yellow, bilateral or radial , often bent at junction of tubes and throats , lobes linear-oblong, acute; anther bases tailed , apical appendages oblong ; style branches: fused portions with minutely hairy nodes, distinct portions minute. Cypselae ± barrel-shaped, ± compressed , smooth or ribbed , apices entire (denticulate in C. benedicta ), glabrous or with fine, 1-celled hairs , attachment scar . lateral (with or without elaiosomes) ; pappi 0 or ± persistent , of 1-3 series of smooth or minutely barbed , stiff bristles or narrow scales . x = 8, 9, 10, 11, 12, 13, 15.

Species ca. 500: introduced ; Eurasia , n Africa, widely introduced worldwide.

Taxonomic limits of Centaurea have been controversial. The genus has great morphologic diversity , and studies have revealed much cytologic (e.g. , N. Garcia-Jacas et al. 1996) and palynologic (e.g., G. Wagenitz 1955) variation as well. During the nineteenth and twentieth centuries, various taxonomists attempted, with limited success, to divide Centaurea into smaller genera or workable infrageneric taxa. The relations of several satellite genera have been controversial as well.

Recent molecular phylogenetic studies (A. Susanna et al. 1995; N. Garcia-Jacas et al. 2000, 2001) have begun to clarify relationships within Centaurea and between Centaurea and other genera. These studies make it clear that Centaurea as traditionally defined is polyphyletic, and that generic boundaries should be realigned if monophyletic taxa are to be recognized. Some taxa traditionally included within Centaurea (e.g., the two native North American species, Centaurea americana and C. rothrockii) fall outside the redefined generic boundaries and are here treated in Plectocephalus. Others usually placed into segregate genera (e.g., Cnicus benedictus) are firmly nested within Centaurea. Because the type species of Centaurea (C. centaurium Linnaeus, an African species) falls outside the main lineage of the genus, a proposal has been made to conserve Centaurea with a different type species (W. Greuter et al. 2001), thereby maintaining the nomenclatural stability of most of the numerous species that do fall within the principal Centaurea clade.

Although several Centaurea species are widely established as members of the North American flora , and some of these are widely distributed invasive weeds , some of the taxa listed by J. T. Kartesz and C. A. Meacham (1999) are apparently waifs and not permanent members of the flora. These taxa are discussed informally immediately below.

Although Cnicus has usually been recognized as a distinctive monotypic genus, it has been merged into Centaurea by various authors (e.g., K . Bremer 1994; G. Wagenitz and F. H. Hellwig 1996) . Recent molecular systematic studies (N. Garcia-Jacas et al. 2000) provide additional evidence that it is nested within Centaurea.[1]

Physical Description

Species Centaurea depressa

Annuals, 20-60 cm. Stems usually several-many from base , spreading , ± openly branched distally, loosely gray-tomentose. Leaves ± loosely gray-tomentose; basal and proximal cauline petiolate , blades oblong , 5-10 cm, margins entire or pinnatifid with terminal segment largest, apices obtuse ; mid and distal cauline sessile, linear-lanceolate to oblong, blades usually not much smaller, entire, mucronate . Heads radiant, borne singly, pedunculate . Involucres ovoid to campanulate , 15-20 mm. Phyllaries: bodies green, ovate (outer) to oblong (inner), glabrous , margins and erect appendages silvery white to brown, scarious , fringed with slender teeth 1.5-2 mm. Florets 25-35; corollas of sterile florets spreading, dark blue, 25-30 mm, enlarged, those of fertile florets purple, ca. 15 mm. Cypselae brown, 4.5-6 mm, puberulent near attachment scar , otherwise glabrous; pappi of outer series of unequal stiff bristles 2-8 mm, inner series of slender scales ca. 1.5 mm. 2n = 16 (Armenia). [source]

Habit: Forb/herb

Flowers: Bloom Period: February, March, April, May, June, July.

Habitat

Disturbed ground ; 50-1400 m [2].

Biology

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Reproduction

Duration: Annual , Biennial

Taxonomy

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Domain: Eukaryota () - Whittaker & Margulis,1978 - eukaryotes
- Kingdom: Plantae () - Haeckel, 1866 - Plants
  - Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
    - Phylum: Tracheophyta () - Sinnott, 1935 ex Cavalier-Smith, 1998 - Vascular Plants
      - Subphylum: Euphyllophytina ()
        Class: Spermatopsida () - Brongniart, 1843
        Subclass: Asteridae () - Takhtajan, 1967
        Superorder: Campanulanae () - Takhtajan Ex Reveal, 1992
        Order: Asterales () - Lindley, 1833
        Family: Compositae () - Giseke, 1792, nom. cons., nom. alt.
        Subfamily: Carduoideae ()
        Tribe: Cardueae ()
        Subtribe: Centaureinae ()
        Genus: Centaurea () - C. Linnaeus, 1753 - Knapweed, star thistle, cornflower [Greek kentaurieon, ancient plant name associated with Chiron, a centaur famous for knowledge of medicinal plants]
        Specific epithet: depressa - M. Bieberstein, Fl. Taur.-Caucas. 2: 346. 1808.
        Botanical name: - Centaurea depressa Bieb. M. Bieberstein, Fl. Taur.-Caucas. 2: 346. 1808.

Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Place of publication : Fl. taur.-cauc. 2:346. 1808

Name verified on 06-Nov-1985 by ARS Systematic Botanists. Last updated: 23-Aug-1994

Similar Species

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Members of the genus Centaurea

ZipcodeZoo has pages for 82 species, subspecies, varieties, forms, and cultivars in this genus:

More Info

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Notes

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Contributors

Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed March 27, 2012.

Data Sources

Accessed through GBIF Data Portal November 28, 2007:

GBIF-Spain, Institut Botanic de Barcelona, BC
GBIF-Spain, Real Jardin Botanico
, Vascular Plant Herbarium
GBIF-Spain, Universidad de Almería, HUAL
GBIF-Spain, Universidad de Oviedo. Departamento de Biología de Organismos y Sistemas: FCO
The Swedish Museum of Natural History
, Herbarium of Oskarshamn
Tiroler Landesmuseum Ferdinandeum, Tiroler Landesmuseum Ferdinandeum

Identifiers

Biodiversity Heritage Library NamebankID: 2670832
Catalogue of Life Accepted Name Code: ITS-506891
Global Biodiversity Information Facility Taxonkey: 13727278
Globally Unique Identifier: urn:lsid:ipni.org:names:190353-1
GRIN Nomen Number: 9818
Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 506891
U.S.D.A. Plant Symbol: CEDE10
Zipcode Zoo Species Identifier: 29310

Footnotes

David J. Keil, Jörg Ochsmann "Centaurea". in Flora of North America Vol. 19, 20 and 21 Page 52, 57, 58, 67, 83, 84, 96, 171, 172, 176, 177, EFloras.org. [back]
"Centaurea depressa". in Flora of North America Vol. 19, 20 and 21 Page 183, 184. Oxford University Press. Online at EFloras.org. [back]

Centaurea depressa

Overview

Interesting Facts

Common Names

Description

Family Compositae

Genus Centaurea

Physical Description

Species Centaurea depressa

Habitat

Biology

Reproduction

Taxonomy

Notes

Similar Species

Members of the genus Centaurea

More Info

Further Reading

Notes

Contributors

Data Sources

Identifiers

Footnotes