Worm fern, mean

Dryopteris filix-mas (from Greek drys/dryos = oak and pteris = fern; fern often growing on old oak trees), the common or true worm fern, is a deciduous plant species that reaches a height of 30cm to 140cm. It belongs to the genus of the worm fern (Dryopteris) within the family of worm fern plants (Dryopteridaceae). The plant is widely distributed in the temperate zones of the northern hemisphere.

The large leaves of Dryopteris filix mas are bipinnate and pointed. The worm fern develops a strong rhizome that stores a fatty oil and sugar. Dryopteris filix mas is the parent plant of Rhizoma filicis (Radix filicis), the dried rhizome.
The ethereal extract of Rhizoma filix-mas was used as a tapeworm remedy (roundworms). Obsolete today due to its toxicity.

Worm fern leaves are fatal for sheep and horses after a few hours, 100 g for cattle after about 4 hours.