Dryopteris filix-mas

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Dryopteris filix-mas, the male fern, is a common fern of the temperate zones in the Northern Hemisphere. It happens in much of Europe, Asia, and North America. It likes damp, shaded places in woodlands, and also shady spots on hedge banks, rocks, and scree. Near its northern range limit, it can grow in sunny, well‑drained sites. It is more common in Europe than in North America.

Appearance and life cycle
- The leaves are semi‑evergreen and upright, growing up to about 150 cm tall, with a single crown on the rootstock.
- The fronds are bipinnate, with 20–35 leaflets (pinnae) on each side of the central stem.
- The leaf tips taper, and the lowest leaflets are about half the length of the middle ones.
- The leaf stalks have orange‑brown scales.
- On the underside of mature fronds, five or six spore cases (sori) appear in two rows. When the spores are ready, the protective coverings (indusia) shrivel and release the spores, usually from August to November.
- This fern can hybridize easily with Dryopteris affinis (scaly male fern) and Dryopteris oreades (mountain male fern).

Names and uses
- Historically it has been called worm fern because it was once used to treat tapeworms.
- The species name filix-mas means “male fern,” reflecting an old belief that this plant was the male counterpart of the common lady fern.

Cultivation and culture
- It is a robust, vigorous plant and many garden cultivars have been developed.
- Some cultivars have won the Royal Horticultural Society’s Award of Garden Merit.

Finland note
- In Nurmijärvi, Finland, this plant is a title plant because a local pharmaceutical factory (1899–1964) used its rhizomes to make medicines for cestodes and liver fluke in sheep. The rhizomes are toxic, and taking too large a dose can cause poisoning, blindness, and even death.