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Common Name: Giant Holly Fern

General Information

Polystichum munitum is a Evergreen Fern up to 1.00 metres tall.
It is harvested from the wild for local use as a food, medicine and source of materials.

Known Hazards

Although we have found no reports of toxicity for this species, a number of ferns contain carcinogens so some caution is advisable[].
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[].

Botanical References

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Range

Western N. America - Alaska to California.

Habitat

There are two distinct varieties, var. munitum grows in moist coniferous woods, var. imbricans grows in rock crevices and rocky soils in dry coniferous soils[]. Forms extensive colonies[].

Properties

Edibility Rating
Medicinal Rating
Habit	Evergreen Fern
Height	1.00 m
Cultivation Status	Wild

Cultivation Details

Very hardy and easily grown in light shade in any reasonable soil[]. Prefers a sandy humus-rich soil in a shady position that is moist even in winter[]. Tolerates part sun for up to 6 hours a day if the soil remains moist[]. It is possible that the var. imbricans will succeed in drier soils[]. Prefers a pH in the range 6.5 to 7.5[].
Members of this genus are rarely if ever troubled by browsing deer[].
A very ornamental plant[], it is a robust clump-forming species[].
Remove old fronds from the plant in the spring because they may harbour fungal diseases[].

Edible Uses

Root - roasted[, , , ]. Peeled and then baked like potatoes[]. The roots were generally viewed by the native North American Indians mainly as a famine food for use when little else was available[]. The roots were generally harvested in the spring, before the plant came into growth then cooked and peeled before being eaten[].

Medicinal

An infusion of the fronds has been used as a wash or poultice to treat boils and sores[, ].
The young shoots have been chewed and eaten as a treatment for cancer of the womb and to treat sore throats and tonsillitis[]. The leaves have been chewed by women to facilitate childbirth[].
The sporangia have been crushed and applied as a poultice to burns, sores and boils[, ].
A decoction of the rhizomes has been used in the treatment of dandruff[, ].

Other Uses

The leaves are used for lining boxes, baskets, fruit drying racks etc and as a stuffing material in bedding[, , ].
A decoction of the rhizome treats dandruff[].
Plants can be grown as a ground cover and are best spaced about 1 metre apart each way[].

Propagation

Spores - best sown as soon as they are ripe, though they can also be sown in the spring. Sow them on the surface of a humus-rich sterilized soil. Keep the compost moist, preferably by putting a plastic bag over the pot. Pot on small clumps of plantlets as soon as they are large enough to handle and keep humid until they are well established. Do not plant outside until the ferns are at least 2 years old and then only in a very well sheltered position.
Division. This is best done in the spring.