The Temperate Database is in the process of being updated, with new records being added and old ones being checked and brought up to date where necessary. This record has not yet been checked and updated.
Common Name: Giant Holly Fern
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.
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[
Western N. America - Alaska to California.
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[
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[
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[
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[
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[
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.