The series was first classified by Diels in 'Die Natürlichen Pflanzenfamilien' (Edited by H. G. A. Engler and K. Prantl) in 1930.

It was further expanded by Lawrence in Gentes Herb (written in Dutch) in 1953.

[1][2][3][4] This is a group of mainly moisture loving plants from Europe, Asia and North America.

[6] The leaves have small blackish spots along the veins.

This trait means that the species can tolerate moist soils.