prickly sow thistle

(Sonchus asper)

Conservation Status
prickly sow thistle
  IUCN Red List

not listed


NNA - Not applicable

SNA - Not applicable


not listed

Wetland Indicator Status
  Great Plains

FAC - Facultative


FACU - Facultative upland

  Northcentral & Northeast

FACU - Facultative upland


Prickly sow thistle is a 4 to 60 tall, erect, perennial forb that rises on one or more stems from a taproot.

The stems are erect, hollow between the nodes, hairless, and often somewhat covered with a whitish, waxy bloom (glaucous). They occasionally branch near the top. The base of the stem is soft, not woody. When broken the stems exude a milky sap.

Middle stem leaves are alternate, inversely egg-shaped to lance-shaped, 2 to 11¾ long, and to 6 wide. They are irregularly, deeply lobed (pinnatifid) with 2 to 5 more or less triangular lobes per side. At the base of the leaf blade is a pair of ear-like projections (auricles) that often wrap around more than half of the stem. The auricles are always rounded. The upper surface of the leaf blade is hairless and shiny. The lower surface paler, hairless, and sometimes somewhat glaucous. The margins have sharp, spreading teeth with prickles at the tip. Basal and lower stem leaves are similar and are on winged leaf stalks. Upper leaves become gradually smaller, less lobed or unlobed, and have more prominent auricles.

The inflorescence is a loose, corymb-like cluster of several flower heads at the end of the stem. The stalks of the inflorescence are usually hairless, occasionally sparsely covered with reddish-brown, spreading, glandular hairs.

The flower heads are to 1 in diameter when fully open. The whorl of bracts at the base of the flower head (involucre) is to ½ long and either contracted at the tip (bell-shaped) or not contracted at the tip (pitcher-shaped). The bracts of the involucre are hairless. Each flower head has 80 to 250 yellow ray florets and no disk florets. The ray florets are 5 16 to long and have 5 small teeth at the tip. The flat, spreading, strap-like portion at the end of the ray floret is shorter than the tube portion at the base.

The fruit is a long achene with usually 3 prominent ribs on each face (6 total) and a smooth, not wrinkled, surface. There is a tuft of microscopically barbed hairs at the tip.




4 to 60


Flower Color




Similar Species


Common sow thistle (Sonchus oleraceus) leaf auricles are triangular to lance-shaped, usually sharply pointed, rarely rounded, and wrap around no more than half of the stem. The upper surface of the leaf blade is not shiny. The achene is wrinkled and 3 or 5 ribbed.

Perennial sow thistle (Sonchus arvensis) stem is hard and sometimes woody at the base. The leaf auricles may be rounded or pointed, and wrap around no more than half of the stem. The upper surface of the leaf blade is dull or only slightly shiny. The flower heads are larger, 1 to 1¾ in diameter. The involucre is longer, 9 16 to long. The ray florets are longer, to 1 long. The achene is prominently 5 to 8 ribbed and is wrinkled.

Prickly lettuce (Lactuca serriola) leaves have a row of prickles along the midvein on the underside.

Thistle (Cirsium spp., Carduus spp.) stems and leaves do not have milky sap.


Streambanks, river banks, pastures, field edges, roadsides, disturbed areas.




July to October


Pests and Diseases






Distribution Map



2, 3, 4, 5, 7, 22, 28, 29, 30.




Native to Africa, Asia, and Europe, and the Indian subcontinent. Introduced and naturalized in North America.





  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Cichorioideae (chicories, dandelions, and allies)  
  Tribe Cichorieae (lettuce, chicory, dandelion, and salsify)  
  Subtribe Hyoseridinae  
  Genus Sonchus (sow thistles)  

Subordinate Taxa






Sonchus asper ssp. asper

Sonchus asper ssp. glaucescens

Sonchus nymanii


Common Names


perennial sowthistle

prickly sow thistle

prickly sowthistle

rough sow thistle

spiny sow thistle

spiny sowthistle

spiny-leaf sow-thistle













A dry, one-chambered, single-seeded seed capsule, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.



A small, ear-like projection at the base of a leaf or at the junction of a grass blade and stem.



A flat-topped or convex inflorescence in which the stalked flowers grow upward from various points on the main stem to approximately the same horizontal plane. The outer flowers open first.


Glandular hairs

Hairs spread over aerial vegetation that secrete essential oils. The oils act to protect against herbivores and pathogens or, when on a flower part, attract pollinators. The hairs have a sticky or oily feel.



Pale green or bluish gray due to a whitish, powdery or waxy film, as on a plum or a grape.



A whorl of bracts beneath or surrounding a flower or flower cluster.



The small swelling of the stem from which one or more leaves, branches, or buds originate.



Deeply cut, more than half way to the midrib but not to the midrib, into lobes that are spaced out along the midrib; the lobes do not form separate leaflets.



A thin, flat, membranous, usually transparent appendage on the margin of a structure.

Visitor Photos

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Flower Head

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  Sonchus asper
Susanne Wiik
  Sonchus asper  

Sharp-fringed sow thistle, stivdylle

  Rough Sow-thistle
Wez Smith
  Rough Sow-thistle  

Rough Sow-thistle (Sonchus asper).

  Spiny Sowthistle (Sonchus asper)
Andree Reno Sanborn
  Spiny Sowthistle (Sonchus asper)  



Visitor Videos

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Other Videos
  Sharp-fringed Sow Thistle (Sonchus asper) - 2013-06-01

Published on Jun 3, 2013

Sonchus asper (Sharp-fringed Sow Thistle, Prickly Sow Thistle, Spiny Sow Thistle, or Spiny-leaved Sow Thistle) is an annual plant with spiny leaves and yellow flowers resembling those of the dandelion.

De Gekroesde melkdistel of Ruwe melkdistel (Sonchus asper) is een kruidachtige, eenjarige plant uit de composietenfamilie (Compositae oftewel Asteraceae).

  Sonchus asper

Published on Jun 24, 2014

Prickly Sow-Thistle - Annual or Biennial plant up to a meter tall. Alternate leaves without stalks seem to wrap around the stems. Clusters of yellow ray flowers. Milky latex oozes from broken stems. Widespread introduced plant from Europe.

  What's That Weed? Spiny-Leaved Sow Thistle

Uploaded on Jun 16, 2011

"Survival Doc" finds Spiny-Leaved Sow Thistle (Sonchus asper) in his front yard and discusses how to identify wild plants that can be used as an emergency survival food or herbal medicine.

  Prickly Sow Thistle with Birdsong by a White Eyed Verio
Dustie Meads

Published on Apr 21, 2012

Northwest Arkansas, while walking along Sugar Creek I happened upon this beautiful (of course there are many who would not call a thistle beautiful...but I think it is) prickly sow thistle. While I was shooting this video, a bird from somewhere in the forest which lined both sides of the creek began a serenade. The bird you hear in the background has been identified for me as a White Eyed Verio.






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