- Spear thistle, Common thistle, Fuller's thistle
- Cirsium lanceolatum, Carduus lanceolatus, Carduus vulgaris
- An upright, biennial plant with a taproot, reaching 2-6 feet tall.
- tipped with long, sharp spines
- pale or wooly beneath
- deeply lobed
- prickly wings
- hairy at maturity
- 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.
- 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
Key ID Features:
- thorny stem
- large flower heads
- rigid yellow-tipped spines on bracts
- 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.
- 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