This exceedingly prickly thistle has been named soldier thistle, as it is well armed with long stiff spines, attacking anything which approaches. The leaves and stems are covered in a waxy coating giving it a bluish hue, the thorns are yellow and the flowers, which are present fleetingly in mid summer are purple.It is abundant in neglected olive groves and abandoned fields.

Picnomon incarna is the only species in the genus Picnomon: this suggests it is an ancient species. Most likely the genus once had many species but most have become extinct. The thistles certainly have a prehistoric look about them.