Plant Image
Flowers
89A south of Flagstaff


Yavapai County Native & Naturalized Plants

Acroptilon repens - hardheads

Synonyms: Centaurea repens, Centaurea picris
Other Common Names: Russian knapweed
Plant Form: Forb

Family: Asteraceae


   
 
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Flower head
Max Licher @http://swbiodiversity.org
Leaf
Patrick Alexander @http://swbiodiversity.org
Plant - summer
89A south of Flagstaff
Max Licher @http://swbiodiversity.org
Max Licher @http://swbiodiversity.org
Forb Plant Description

Origin: Introduced   Life Cycle: Perennial
General Desc: A creeping forb that forms dense colonies from a deep spreading root system. Stems grow up to 4 feet and are erect and openly branched. It reproduces primarily by vegetative means, and can spread rapidly.
Identification notes: Rhizomatous perennial; stems and leaves hairy, lower leaves pinnately lobed, middle ones toothed, upper ones smooth margined, lower leaves not much larger than upper. Pink to purplish flower heads of disc only flowers, inner bracts densely hairy, pointed.
Height: 18 to 36 inches


Habitat

Habitat Description: Cultivated fields, orchards, pastures, and roadsides.
Plant Communities: Disturbed Areas
Elevation: 3000 - 7000 feet


Flower Characteristics

Color: Pink to pinkish-purple     Shape: Daisy or dandelion-like not in clusters     Tubular: N     Flowering Period: Jun - Sep
Description: Flower heads are solitary and at the tip of leafy branches. Bracts are pointed with papery tips. Flowers have a thistle-like appearance.


Leaf and Stem Characteristics

Leaf Color: Grayish-green, bluish-green     Leaf Type: Simple     Leaf Shape: Narrow     Leaf Margin: Lobed     Leaf Attachment: Alternate     Leaves Clasp: N
Hairs: Leaves and stems     Spines: N
Leaf Description: Lower leaves are 2 to 4 inches long and deeply lobed. Upper leaves are not much smaller, generally with smooth margins, but can be slightly lobed. Shoots and leaves are covered with dense gray hairs.


Fruit and Seed Characteristics

Fruit Type: Achene
Fruit Notes: Achene bristles white, 1/4 to 1/2 inch long.
Seed Notes: A single Russian knapweed plant can produce about 1,200 seeds per year.



  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 7.0  
http://cals.arizona.edu/yavapaiplants/SpeciesDetailForb.php  
Last Updated: May 10, 2017  
Content Questions/Comments: Email Jeff Schalau  
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