Species Detail Forb

Flower head Aspen Creek Tr - Sue Smith		Yavapai County Native & Naturalized Plants Centaurea biebersteinii - spotted knapweed Synonyms: Centaurea stoebe ssp. micranthus, Acosta maculosa, Centaurea maculosa Plant Form: Forb or Subshrub Family: Asteraceae
Flower head Aspen Creek Tr - Sue Smith


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Bracts Aspen Creek Tr Sue Smith	Leaf Aspen Creek Tr Sue Smith	Leaf attachment Aspen Creek Tr Sue Smith

Forb Plant Description

Origin: Introduced Life Cycle: Biennial or perennial Similar Species: Centaurea diffusa
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: Spotted knapweed is distinguished reliably by its "spots" or blackened bract ends. Pink to purple disc flowers only. Leaves divided into very narrow lobes, grayish-green.
Height: 8 inches to 4 feet

Habitat

Habitat Description: It prefers dry, coarsely textured soils that drain well, especially in south facing locations. It readily invades disturbed sites, choking out native vegetation, once established, it moves into surrounding more pristine areas.
Plant Communities: 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 disc-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: Gray green to 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 dotted with resin, narrow and deeply lobed, lobes are toothed at their end.

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 8.0 http://cales.arizona.edu/yavapaiplants/SpeciesDetailForb.php Last Updated: Dec 13, 2022 Content Questions/Comments: Email Matt Halldorson Legal Disclaimer