Linum catharticum, also known as purging flax, or fairy flax, is an herbaceous flowering plant in the family Linaceae, native to Great Britain, Iceland, central Europe and Western Asia. It is an annual plant and blooms in July and August.
It is a known host of the pathogenic fungus flax rust (Melampsora lini).
References Helgi Hallgrímsson & Guðríður Gyða Eyjólfsdóttir (2004). Íslenskt sveppatal I - smásveppir [Checklist of Icelandic Fungi I - Microfungi. Fjölrit Náttúrufræðistofnunar. Náttúrufræðistofnun Íslands [Icelandic Institute of Natural History]. ISSN 1027-832X