[4] Some sources claim it originates in southern Europe and Asia, but has been extensively naturalized elsewhere.

Upon fruiting, these two flowers ripen into two brown to black achenes and they are completely enveloped by the involucre, which becomes a bur.

The bur, being buoyant, easily disperses in the water for plants growing along waterways.

However, the bur, with its hooked projections, is obviously adapted to dispersal via mammals by becoming entangled in their hair.

Once dispersed and deposited on the ground, typically one of the seeds germinates and the plants grows out of the bur.