Centaurea L.

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The blue spidery flowers of mountain bluet bloom in the spring and summer. They are ideal for borders, cottage gardens, and even rock gardens. Here, placed amongst hostas, they thrill after the tulips have shed most of their petals and the alliums are beginning to shine with their beautiful tall purple globe shaped flowers of spring. It's the natural order of the gardens star appearances.

Early morning dew graces the buds as they begin to break open on a foggy morning. In the shady areas of this garden lily of the valley is in full bloom, and the scent wafts through the air at all hours of the day.

Dew covered Mountain Bluet (Centaurea montana)   

It blooms in late May and early June in hardiness zone 5.

Mountain bluet, also known as perennial bachelor buttons is included in the aster family. It is found as a native in central and southern Europe.

Cyanus montanus, latifolius vel Verbaculum Cyanoides

 Hortus Romanus juxta systems Tournefortianum paulo

1772-1793

Bonelli, Giorgio (b. 1724) (Author)

Martelli, Niccoló (1735-1829) (Editor)

Source: From The New York Public Library

 Grow in a full or partial sun exposure. In a partial sun exposure the plant is more likely to get mildew, but they can be cut back and the foliage removed. At this point the plant will regrow  and bloom a second time during the summer. It will survive in hardiness zones 3-8 with medium to dry water conditions. One to two feet is the approximate height and spread and it will reseed in situ, but is not invasive. The plants should be divided every three years.

CORNFLOWERS

Centaurea cyanus

, 

Plant lovers, gardeners, and botanists sometimes experience frustration trying to nail down an exact plant that they have seen and might like to add to their own garden or plant knowledge. Several professional groups are working hard to speak in the same language for identity purposes and recognize ancestry, ethnobotonists, are the Henry Lewis Gates of "Finding your Roots" fame.

Below, I have combined the cornflowers and knapweed from the Ladybird Johnson Wildflower Center with those listed at the USDA site and the ITIS site.

DATABASE	SYMBOL CODE	TAXA	COMMON NAME	ITIS - ACCEPTED	NATIVE		CITE
USDA	CENTA	Centaurea L.	knapweed	Centaurea L.
USDA	CENTA	Centaurea L.	knapweed	Centaurea L.
ITIS	TSN 36950	Centaurea L. – accepted – knapweed, star thistle	knapweed, starthistle	Centaurea L.
IPNI	330045-2	Centaurea L	knapweed	Centaurea L.
IPNI	56874-3	Centaurea L	knapweed	Centaurea L.
ITIS	TSN 36951	Centaurea americana Nutt. – not accepted – American basketflower, American star thistle, American star-thistle	American basketflower, American star thistle, American star-thistle	Plectocephalus americanus (Nutt.) D. Don	USA: AZ, NM, TX, OK, KS, AR, MO, IA, IL, WI, GA, NY; MEX: Chihuahua, Coahuila, Durango, Hidalgo, Nuevo Leon, Oaxaca, Querétaro, San Luis Potosí, Sonora, tamaulipas; HONDURAS; EL SALVADOR.		https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=36951#null/
WORLD PLANTS		Plectocephalus americanus (Nutt.) https://www.worldplants.de/world-plants-complete-list/complete-plant-list/?name=Plectocephalus-americanus#g-		Plectocephalus americanus (Nutt.)	USA: AZ, NM, TX, OK, KS, AR, MO, IA, IL, WI, GA, NY; MEX: Chihuahua, Coahuila, Durango, Hidalgo, Nuevo Leon, Oaxaca, Querétaro, San Luis Potosí, Sonora, tamaulipas; HONDURAS; EL SALVADOR.		Hassler, Michael (2004 - 2022): World Plants. Synonymic Checklist and Distribution of the World Flora. Version 13.0; last update May 29th, 2022. - www.worldplants.de. Last accessed dd/mm/yyyy.
COL	COL Identifier 4K3BT	Plectocephalus americanus (Nutt.) https://www.catalogueoflife.org/data/taxon/4K3BT		Plectocephalus americanus (Nutt.)
IPNI	189870-1	Centaurea americana Nutt.	American star-thistle	Plectocephalus americanus (Nutt.) D.Don, Brit. Fl. Gard. [Sweet] 4(ser. 2, 1): t. 51 (1830).			IPNI (2022). International Plant Names Index. Published on the Internet http://www.ipni.org, The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Botanic Gardens. [Retrieved 15 March 2022].
USDA	CEAM2	Centaurea americana Nutt.	American star-thistle	Plectocephalus americanus (Nutt.) D. Don	USA: AZ, NM, TX, OK, KS, AR, MO, IA, IL, WI, GA, NY; MEX: Chihuahua, Coahuila, Durango, Hidalgo, Nuevo Leon, Oaxaca, Querétaro, San Luis Potosí, Sonora, tamaulipas; HONDURAS; EL SALVADOR.
LBJWFC	CEAM2	Centaurea americana	American Basket-flower American Star-thistle Basket-flower Star Thistle Shaving Brush Basket Flower	Plectocephalus americanus (Nutt.) D. Don	USA: AZ, NM, TX, OK, KS, AR, MO, IA, IL, WI, GA, NY; MEX: Chihuahua, Coahuila, Durango, Hidalgo, Nuevo Leon, Oaxaca, Querétaro, San Luis Potosí, Sonora, tamaulipas; HONDURAS; EL SALVADOR.
ITIS	TSN 36970	Centaurea rothrockii Greenm. – not accepted – Rothrock's knapweed		Plectocephalus rothrockii (Greenm.) D.J.N. Hind			Retrieved [month, day, year], from the Integrated Taxonomic Information System (ITIS) on-line database, www.itis.gov, CC0 https://doi.org/10.5066/F7KH0KBK
IPNI	51292-2	Centaurea rothrockii		Plectocephalus rothrockii
LBJWFC	CERO	Centaurea rothrockii	Rothrock's Knapweed Rothrock’s Basketflower Mexican Basketflower	Plectocephalus rothrockii (Greenm.) D.J.N. Hind
ITIS	TSN 36974	Centaurea transalpina auct. non Schleich. ex DC. – not accepted – alpine knapweed	alpine knapweed	Centaurea nigrescens Willd.			Retrieved [month, day, year], from the Integrated Taxonomic Information System (ITIS) on-line database, www.itis.gov, CC0 https://doi.org/10.5066/F7KH0KBK
LBJWFC	CETR6	Centaurea transalpina	Alpine Knapweed Tyrol Knapweed Short-fringed Knapweed	Centaurea nigrescens Willd.

Resources.                                                    

Dimmitt, Mark A., A Natural History of the Sonoran Desert (ASDM Press, 2000), Centaurea Rothrockii., 2003. Internet resource. Link

Phylogeny of the Centaurea Group (centaurea, Compositae) Geography Is a Better Predictor Than Morphology. Elsevier, 2014. Internet resource.

   IPNI (2022). International Plant Names Index. Published on the Internet http://www.ipni.org, The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Botanic Gardens. [Retrieved 15 March 2022].         

ITIS (2022) International Taxonomy Information System.   

      

LBJWC (2022) Ladybird Johnson Wildflower Center.    

USDA PLANTS DATA (2022).                 

                                                                                                             

                                                         

    © 2022 by  Hyden Photography

 for 

Grassroots Horticulture

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