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Yavapai County Native & Naturalized Plants

Sonchus asper - spiny sowthistle

Synonyms: Sonchus nymanii
Other Common Names: prickley sowthistle
Plant Form: Forb or Subshrub

Family: Asteraceae

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Forb Plant Description

Origin: Introduced   Life Cycle: Annual
General Desc: This is an annual plant with spiny leaves and yellow dandelion-like flowers. It is native to Europe and is considered to be an undesirable import.
Identification notes: Auricles, (an earlike projection on the base of the leaf), are rounded and achenes are not transversely wrinkled, distinguishes this species from Sonchus oleraceus.
Height: 1 to 6 feet


Habitat Description: An invasive weed found along roadsides, in waste areas, gardens, and cultivated fields. The deep taproot and spiny leaves make it hard to eradicate.
Plant Communities: Disturbed Areas
Elevation: 150 - 7000 feet

Flower Characteristics

Color: Yellow     Shape: Daisy or dandelion-like in round clusters     Tubular: N     Flowering Period: Apr - Sep
Description: The 1 inch flower is made up of ray petals with fringed tips. Clustered flowers are on individual stalks. Dependent on the plant colony, any given plant will flower from late spring to early fall.

Leaf and Stem Characteristics

Leaf Color: Green     Leaf Type: Simple     Leaf Shape: Round or oval     Leaf Margin: Toothed     Leaf Attachment: Basal and alternate     Leaves Clasp: Y
Hairs: No     Spines: Y
Leaf Description: Lower leaves are lobed and toothed with spiny margins; leaves of the stem have sharp, stiff prickles and large rounded basal lobes which clasp the stem. Both the stems and leaves contain a milky sap.

Fruit and Seed Characteristics

Fruit Color: Brown   
Fruit Type: Achene
Fruit Notes: The fruit is flat and three-ribbed on each face and has a cluster of fine hairs attached to the upper end.
Seed Notes: Seeds are wind dispersed.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
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Version 8.0  
Last Updated: Dec 13, 2022
Content Questions/Comments: Email Matt Halldorson  
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