Brittle Bladder Fern

Cystopteris fragilis

Physical Characteristics

Cystopteris fragilis is a deciduous Fern growing to 0.2 m (0ft 8in) by 0.2 m (0ft 8in). See above for USDA hardiness. It is hardy to UK zone 2. The seeds ripen from July to August. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in full shade (deep woodland) or semi-shade (light woodland). It prefers moist soil.

Distribution

Cosmopolitan, found in most areas of the world, including Britain, but only on mountains in Tropics.

Habitats

Woodland Garden Dappled Shade; Shady Edge; not Deep Shade; Ground Cover; North Wall. In. East Wall. In.

Edible Uses

Edible Parts: Root Edible Uses: Root. An emergency food, it is only used when all else fails[172].

Medicinal Uses

Anthelmintic A decoction of the roots has been used as an anthelmintic enema[240]. A cold compound infusion of the plant has been used both internally and externally as a treatment for injury[257].

Known Hazards

Although we have found no reports of toxicity for this species, a number of ferns contain carcinogens so some caution is advisable[200]. Many ferns also contain thiaminase, an enzyme that robs the body of its vitamin B complex. In small quantities this enzyme will do no harm to people eating an adequate diet that is rich in vitamin B, though large quantities can cause severe health problems. The enzyme is destroyed by heat or thorough drying, so cooking the plant will remove the thiaminase[172].