Plant Image
Flower head
Aspen Creek Tr - SS


Yavapai County Native & Naturalized Plants

Centaurea biebersteinii - spotted knapweed

Synonyms: Centaurea stoebe L. ssp. micranthus (Gugler) Hayek
Plant Form: Forb

Family: Asteraceae


   
 
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Bracts
Aspen Creek Tr
SS
Leaf attachment
Aspen Creek Tr
SS
Leaf
Aspen Creek Tr
SS
Forb Plant Description

Origin: Introduced   Life Cycle: Biennial or perennial   Similar Species: Centaurea diffusa Lam
General Desc: This invasive plant grows from a basal rosette in its first year into a bushy plant in its second year, blossoming with a profusion of small flowers for months and generating new rosettes for future growth.
Identification notes: The spotted knapweed is distinguished most reliably by its "spots" or blackened ends on its bracts.
Height: 8 inches to 4 feet


Habitat

Habitat Description: It prefers dry, coarsely textured soils that drain well, especially in south facing locations. However it adapts well to many environments from roadsides to open forests to disturbed sites.
Plant Communities: Desert Scrub, Interior Chaparral, Semidesert Grasslands, Pinyon Juniper Woodland, Montane Conifer Forest, Riparian, Disturbed Areas
Elevation: 1900 - 10000 feet


Flower Characteristics

Color: Pink to purple, rarely white     Shape: Daisy or Dandelion-like not in clusters     Tubular: N     Flowering Period: Jun - Oct
Description: The flower can be 3/4 to 1 inch wide and when fully open is disk-like. The flower emerges from a cone of bracts, which distinguish the plant with their black tips and coarse bristles.


Leaf and Stem Characteristics

Leaf Color: Dark green     Leaf Type: Simple     Leaf Shape: Pinnatifid     Leaf Margin: Toothed     Leaf Attachment: Basal and alternate     Leaves Clasp: N
Hairs: Leaves and stems     Spines: N
Leaf Description: Erect, wiry stems that are green or gray in color branch freely at mid-height, producing 15 or more flowering stems. Leaves, which may be 6 inches long near the stem, are narrow and deeply lobed.


Fruit and Seed Characteristics

Fruit Color: Brown to black   
Fruit Type: Achene
Seed Notes: Seeds are oval with pale lengthwise lines and short fringe on one end.



  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 3.1  
http://prescottnatives.com/SpeciesDetailForb.php  
Last Updated: June 15, 2013  
Content Questions/Comments: Email Jeff Schalau  
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