The field thistle (Cirsium arvense) is common everywhere in France – hence the old French saying: land of thistles, land of millions – with a predilection for fertile, cool, and rather clayey soils. It can resist storms and blooms on sand dunes. It reproduces either thanks to its seeds (up to 5,000 per shoot), or to its root system which allows the plant to progress in spots and provides its extraordinary resistance. Its vertical roots can dig down to several meters deep, and horizontal rhizomes, usually located under the main part, store reserves and emit new shoots. Thistles play a key role in dune maintenance.