Plant Image
Flower head


Yavapai County Native & Naturalized Plants

Cirsium arvense - Canada thistle

Synonyms: Breea arvensis, Carduus arvensis, Cirsium incanum, C. ochrolepidium , C. setosum and more see SEINET.
Plant Form: Forb or Subshrub

Family: Asteraceae


   
 
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Leaves
http://www.inaturalist.org/observations/11511750, CC BY-NC (Attribution-Non-Commercial)
Plant
USDA, NRCS. 2021. PLANTS Database
Forb Plant Description

Origin: Introduced   Life Cycle: Perennial
General Desc: New stems arise from deep creeping roots, resulting in patches of plants; stems slender, smooth, branched above; male, female flowers usually on separate plants; spiny leaves, stems topped by single flower heads of disc flowers only.
Identification notes: Colonies of plants from creeping roots; stems not winged; basal and stem leaves narrow, usually lobed, lobes spine tipped; flower heads of disc flowers only, single or in stemmed clusters, male and female flower heads usually on separate plants.
Height: 12 to 39 inches


Habitat

Habitat Description: Disturbed sites, fields, pastures, roadsides, forest openings.
Plant Communities: Desert Scrub, Interior Chaparral, Semidesert Grasslands, Pinyon Juniper Woodland, Montane Conifer Forest, Disturbed Areas
Elevation: Below 8530 feet


Flower Characteristics

Color: Pinkish-purple, white     Shape: Daisy or dandelion-like in elongated clusters     Tubular: N     Flowering Period: Jun - Oct
Description: 1 to several flower heads at ends of stems; female flower heads urn-shaped, less than 1 inch across; male flower heads smaller and rounder; smooth green bracts below flowers look like small green leaves or scales; plants usually all female or all male.


Leaf and Stem Characteristics

Leaf Color: Dark green     Leaf Type: Simple     Leaf Shape: Narrow     Leaf Margin: Lobed     Leaf Attachment: Alternate     Leaves Clasp: Y
Hairs: Leaves and stems     Spines: Y
Leaf Description: Grooved, upright, hollow, woody stems, branch near top; alternate, lance-shaped leaves, dark green, shiny surface, slightly clasping stem; lower leaves largest, size decreases upward; leaf edges smooth to irregularly lobed, spiny margined.


Fruit and Seed Characteristics

Fruit Color: Brown   
Fruit Type: Achene
Fruit Notes: 1/4 inch long; tufted with long white hairs.


  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  
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