Bull Thistle
Cirsium vulgareAsteraceae
Whole Plant
Whole Plant
Flower
Fruit
Whole PlantWhole PlantFlowerFruit
Leaf
Stem
Habitat
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Photos (c) Cheryl Comeau Beaton unless otherwise noted

Synonyms:

  • Spear thistle, Common thistle, Fuller's thistle
  • Cirsium lanceolatum, Carduus lanceolatus, Carduus vulgaris

The Plant:

  • An upright, biennial plant with a taproot, reaching 2-6 feet tall.

The Leaves:

  • alternate
  • tipped with long, sharp spines
  • pale or wooly beneath
  • deeply lobed

The Stem:

  • spiny
  • prickly wings
  • hairy at maturity

The Flowers:

  • Reddish purple flowers with large heads and many petals. Flowers are solitary or in groups of two or three. Bracts have rigid, yellow-tipped spines on them.

The Fruits:

  • yellowish brown, black or purple streaks
  • narrow yellow band at the top
  • 1/8 inch long and 1/16 inch wide
  • topped with a white pappus (plume-like hairs) up to 1 inch long

The Habitat:

  • roadsides
  • fields

Dispersal:

  • wind-dispersed seeds

Key ID Features:

  • thorny stem
  • large flower heads
  • rigid yellow-tipped spines on bracts

Similar Species:

  • Resembles Canada thistle (Cirsium arvense) which has creeping roots, smaller flowers, weak prickles, and lacks the thorny stems. There are many native Cirsium species which may resemble Bull thistle. Many of the natives don't have leaves that clasp the stem all the way from node to node, their leaf surfaces are hairy above and below, and are blue-green or gray in color.

Notes:

  • This species can cause agricultural losses by restricting livestock grazing, and is also very aggressive in disturbed areas.

Growth Form: Herb

Origin: Europe, Western Asia, North Africa

Level of Invasiveness for Nantucket: Likely Invasive

Level of Invasiveness for Massachusetts: Not evaluated

Massachusetts Cultivation Restrictions: no




Credits: The Electronic Field Guide to the Invasive Plants of Nantucket (c) 2005-2006 Maria Mitchell Association, EFG Project, UMass Boston