THISTLE

'Thistle' is the common name of a polyphyletic group of flowering plants characterised by leaves with sharp spines or prickles on the margins, mostly in the plant family Asteraceae. Their prickles often occur all over the plant, including on the stem and flat parts of the leaf. These are an adaptation to protect the plant against herbivorous animals, discouraging them from feeding on the plant.
The thistle, in particular ''Onopordum acanthium'' (the cotton thistle or Scotch thistle), is the national flower of Scotland, and is featured in many Scottish symbols and logos. Legend has it that a Viking attacker stepped on one at night and cried out, so alerting the defenders of a Scottish castle. Nowadays many football clubs in Scotland use Thistle in their name, to give themselves both a patriotic and fierce perception by others.
Genera in the Asteraceae with the word thistle often used in their common names include:

★ ''Arctium'' – Burdock

★ ''Carduus'' – Thistle

★ ''Carlina'' – Carline thistle

★ ''Centaurea'' – Star thistle

★ ''Cicerbita'' – Sow thistle

★ ''Cirsium'' – Thistle

★ ''Cnicus'' – Blessed thistle

★ ''Cynara'' – Artichokes, Cardoon thistle

★ ''Echinops'' – Globethistle

★ ''Notobasis'' – Syrian thistle

★ ''Onopordum'' – Cotton thistle, also known as Scotch thistle

★ ''Scolymus'' – Golden thistle or oyster thistle

★ ''Silybum'' – Milk thistle

★ ''Sonchus'' – Sow thistle
Plants in families other than Asteraceae which are sometimes called thistle include:

★ ''Salsola'' – Saltwort, tumbleweed or Russian thistle (family Amaranthaceae)