Species Detail Forb

Flower head		Yavapai County Native & Naturalized Plants Centaurea diffusa - diffuse knapweed Synonyms: Centaurea microcaeathina Other Common Names: white knapweed, tumble knapweed Plant Form: Forb or Subshrub Family: Asteraceae
Flower head


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Plant Max Licher @http://swbiodiversity.org, Usage Rights: Creative Commons Attribution-ShareAlike (CC BY-SA)

Forb Plant Description

Origin: Introduced Life Cycle: Annual or perennial
General Desc: A robust diffusely branched and ball-shaped plant with a large taproot and a basal rosette of leaves. Smaller leaves appear on upright stems.
Identification notes: 1/2 inch long white to pink, blue, or purple flowers with 1/2 inch long involucres and principal phyllaries (bracts) tipped with less than 1/4 inch long spines distinguish this species from other Centaurea sp.
Height: 1 to 2 feet

Habitat

Habitat Description: Listed as a noxious, prohibited weed in Arizona. Diffuse knapweed infests roadsides, waste areas, and dry rangelands.
Plant Communities: Desert Scrub, Interior Chaparral, Semidesert Grasslands, Pinyon Juniper Woodland, Montane Conifer Forest, Riparian, Disturbed Areas
Elevation: Below 7500 feet

Flower Characteristics

Color: White to pink Shape: Daisy or dandelion-like not in clusters Tubular: N Flowering Period: Jun - Aug
Description: Flowers grow out of bell-shaped heads and are surrounded by slender straw-colored spines.

Leaf and Stem Characteristics

Leaf Color: Green Leaf Type: Simple Leaf Shape: Narrow Leaf Margin: Lobed Leaf Attachment: Alternate Leaves Clasp: N
Hairs: Leaves and stems Spines: N
Leaf Description: Leaves are resin spotted and stalkless. Stems are rough to the touch and gray-green.

Fruit and Seed Characteristics

Fruit Color: Dark brown
Fruit Type: Achene
Seed Notes: A single plant can produce as many as 18,000 barrel-shaped seeds per year.


	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