Worm fern, mean

Ferns are among the oldest plants on earth. In the Carboniferous period, around 350 million years ago, ferns were as large as today's trees. Dryopteris filix-mas (from the Greek drys/dryos = oak and pteris = fern; fern that often grows on old oaks), the common or true worm fern, is a deciduous plant species that reaches a height of 30 cm to 140 cm. It belongs to the genus of worm ferns (Dryopteris) within the worm fern family (Dryopteridaceae). The plant is widespread in the temperate zones of the northern hemisphere.

The rootstock, Rhizoma filicis, of the worm fern is used phytotherapeutically.

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 filicis 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.