Hard Shield Fern

Polystichum aculeatum

Physical Characteristics

Polystichum aculeatum is an evergreen Fern growing to 0.8 m (2ft 7in) by 0.5 m (1ft 8in). See above for USDA hardiness. It is hardy to UK zone 5. It is in leaf all year, and the seeds ripen from July to August. Suitable for: light (sandy) and medium (loamy) soils. 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

Europe, including Britain, from Scandanavia south and east to N. Africa, S.W. Asia to China, Japan.

Habitats

Woodland Garden Dappled Shade; Shady Edge; not Deep Shade; Ground Cover;

Edible Uses

Edible Parts: Leaves Edible Uses: Eaten in curries[177]. We have no more details, it is probably the young leaves that are used though it might be the root.

Medicinal Uses

None known

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].