Hartstongue (Asplenium scolopendrium) is a fern that has been used historically in traditional European herbal medicine. Its application for supporting the "Spleen" body system is based primarily on humoral and organ-based concepts in Galenic and later herbal traditions, where the spleen was associated with melancholia, blood purification, and fluid regulation. Hartstongue was thought to be beneficial for the spleen due to its purported cooling and astringent properties, and it appears in some historical herbals as a remedy for spleen-related complaints, often in the form of teas or decoctions.

However, there is minimal to no modern scientific research validating the efficacy of hartstongue for spleen health or function. The plant contains some phenolic compounds and flavonoids, but their relevance to spleen support specifically has not been established. The use of hartstongue for the spleen persists among some traditional herbalists, but this is not supported by clinical studies or robust preclinical evidence. Thus, the justification for using hartstongue to support the spleen rests almost entirely on tradition rather than science, and the evidence strength is low.