21 Types of Thistle Plants With How To Identify Them

Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins. Prickles can also occur all over the plant – on the stem and on the flat parts of the leaves. The stem is upright and usually hairy. Stems have few to many branches. Leaves are green above and covered in dense white hairs below. One to many heads are borne at the end of branches.

The term thistle is sometimes taken to mean precisely prickly plants in the tribe Cardueae (synonym: Cynareae), especially the genera Carduus, Cirsium, and Onopordum, which have dense heads of small, usually pink or purple flowers. Plants of the genus Carduus, sometimes called plumeless thistles, have spiny stems and flower heads without ray flowers. However, plants outside this tribe are sometimes called thistles.

All members of the family produce one or more heads (capitulum) of flowers. Members of the family typically produce two types of flowers, ray flowers and disc flowers and in turn, these can have male and female parts, or either one or the other. The ray flowers look like petals, but each is actually an individual flower. The disk flowers are at the center of the head, inside the ring of ray flowers. Flowers are pink to purple, rarely white. 

Thistle Varieties

  • Scottish Thistle’ (Onopordum acanthium)
  • Spear/Bull Thistle (Cirsium vulgare)
  • Melancholy Thistle (Cirsium heterophyllum)
  • Creeping/Canada Thistle (Cirsium arvense)
  • Meadow Thistle (Cirsium dissectum)
  • Marsh Thistle (Cirsium palustre)
  • Woolly Thistle (Cirsium eriophorum)
  • Slender Thistle (Carduus tenuiflorus)
  • Italian thistle (Carduus pycnocephalus)
  • Slenderflower thistle (Carduus tenuiflorus)
  • Bristly thistle Carduus acanthoides)
  • Musk thistle (Carduus nutans)
  • Artichoke plant (Cynara cardunculus var. scolymus) 
  • Spiny sowthistle (Sonchus asper)

Thistle-Like Plants

  • Carline Thistle (Carlina spp.)
  • Common Knapweed (Centaurea)
  • Blue Sow Thistle (Cicerbita alpina)
  • Globe Thistles (Echinops)
  • Milk Thistle (Silybum marianum)
  • Globe Artichoke (Cynara scolymus)
  • Cardoon (Cynara cardunculus)
  • Sea Hollies (Eryngium)
  • Russian thistle (Kali tragus)