musk thistle

(Carduus nutans ssp. leiophyllus)

Conservation Status
musk thistle (ssp. leiophyllus)
  IUCN Red List

not listed

     
  NatureServe

NNA - Not applicable

SNA - Not applicable

     
  Minnesota

not listed

     
           
Weed Status
   
 

SN – State noxious weed

PS – State prohibited weed seed

     
           
Wetland Indicator Status
     
  Great Plains

FACU - Facultative upland

     
  Midwest

FACU - Facultative upland

     
  Northcentral & Northeast

FACU - Facultative upland

     
           
 
Description
 
 

Musk thistle (ssp.leiophyllus) is a 16 to 78 tall, erect, biennial forb that rises on a single stem from a stout taproot.

The stems are erect, ribbed, and often branched near the top. They may be hairless or covered with short, soft, woolly, matted or tangled hairs. They have small appendages (wings) running the length of the stem and branches except just below the inflorescence. The wings are interrupted, not continuous for the length of the stem. They are irregularly lobed and wavy, each lobe tipped with relatively hard, straw-colored spines.

In the first year the plant appears as a rosette of basal leaves that may be 24 or more in diameter. In the second year it sends up a single flowering stem.

Basal leaves are lance-shaped to broadly elliptic in outline and 4 to 16 long. In the first year they are shallowly lobed, sometimes with a whitish, waxy bloom (glaucous), and irregularly prickled. In the second year they become deeply lobed (pinnatifid), each lobe again lobed (bipinnatifid). The primary lobes are cut up to 80% of the way to the midrib. The ultimate lobes are triangular-shaped and tipped with relatively hard, straw-colored spines. The upper side is dark green and hairless with a light green midrib. The underside is hairless except for sometimes some hairs along the main veins. The margins are often whitish.

Stem leaves are similar, alternate, stalkless, and up to 12 long, becoming smaller and less divided as they ascend the stem. The ultimate lobes are lance-shaped to egg-shaped. The base of the leaf continues down the stem and forms a pair of spiny wings. Upper stem leaves are lance-shaped and ½ to 6 long.

The inflorescence is a usually a single, long-stalked flower head at the end of the stem and each branch, sometimes a cluster of a few flower heads. The flower stalk is relatively naked—leafless and not winged—but sometimes has a few small, scattered bracts. It is often densely covered with felty hairs. The flower head nods (droops) ninety degrees when mature.

The whorl of bracts at the base of the flower head (involucre) is cup-shaped to somewhat bell-shaped, ¾ to 2 long, and ¾ to 2¾ wide. The bracts of the involucre (phyllaries) are lance-shaped to egg-shaped, spreading to bent backward, to 2 long, 1 16 to ¼ wide, and sometimes purple at the tip. They are abruptly tapered to a 1 32 to long spine at the tip. They are hairless.

The flower heads are ¾ to 2¾ wide. They have numerous purplish to white tubular flowers.

The fruit is a golden to brown, to 3 16 long achene with whitish, barbed hairs attached.

 
     
 

Height

 
 

16 to 78

 
     
 

Flower Color

 
 

Purple to white

 
     
 

Similar Species

 
 

Musk thistle (Carduus nutans ssp. macrocephalus) upper and lower leaf surfaces are moderately hairy. The flower stalk is short. The phillaries are covered with cobwebby hairs.

Musk thistle (Carduus nutans ssp. macrolepis) involucral bracts are evenly tapered, not abruptly tapered, at the tip.

 
     
 
Habitat
 
 

Disturbed areas, roadsides.

 
     
 
Biology
 
 

Flowering

 
 

June to October

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

7.

 
  7/14/2013      
         
 

Nativity

 
 

Native of Asia and Europe. Introduced and naturalized in North America.

 
         
 

Occurrence

 
 

 

 
         
 
Taxonomy
 
  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  
 

Order

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Carduoideae (thistles and allies)  
  Tribe Cynareae (= Cardueae)  
  Subtribe Carduinae (thistles and burdocks)  
  Genus Carduus (plumeless thistle)  
  Species Carduus nutans (musk thistle)  
       
 

Cardueae is a synonym of the tribe name. Cynareae was published first and has precedence. Nevertheless, most sources use the name Cardueae for the tribe.

 
       
 

Synonyms

 
 

Carduus nutans var. leiophyllus

Carduus nutans var. vestitus

 
       
 

Common Names

 
 

musk thistle

nodding plumeless thistle

nodding plumeless-thistle

nodding thistle

plumeless thistle

 
       

 

 

 

 

 

 

 

 

 

 

 

Glossary

Bipinnatifid

Twice pinnatifid. Cut deeply into lobes with each lobe also cut into deep lobes.

 

Bract

Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.

 

Glaucous

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

 

Involucre

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

 

Phyllary

An individual bract within the involucre of a plant in the Asteraceae family.

 

Pinnatifid

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.

 

Sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

 

Wing

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

       
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Plant

  musk thistle (ssp. leiophyllus)   musk thistle (ssp. leiophyllus)
       

Inflorescence

  musk thistle (ssp. leiophyllus)    
       

Flower Head

  musk thistle (ssp. leiophyllus)    
       

Stem

  musk thistle (ssp. leiophyllus)    
       
       

 

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