John the Evangelist describes it like this:
1 Then Pilate took Jesus and flogged him. 2 And the soldiers twisted together a crown of thorns and put it on his head and arrayed him in a purple robe. 3 They came up to him, saying, "Hail, King of the Jews!" and struck him with their hands. (John 19:1-3 ESV)
Following Genesis 3:17-19—
17 And to Adam he said,
"Because you have listened to the voice of your wife and have eaten of the tree of which I commanded you, 'You shall not eat of it,' cursed is the ground because of you; in pain you shall eat of it all the days of your life; 18 thorns and thistles it shall bring forth for you; and you shall eat the plants of the field. 19 By the sweat of your face you shall eat bread, till you return to the ground, for out of it you were taken; for you are dust, and to dust you shall return." (ESV)
— thorns were seen by Christian writers as emblems of The Fall of Man.