Practical ecological knowledge for the temperate reader.

Licorice Fern - Polypodium glycyrrhiza

Family: Ferns - Polypodiaceae Family


"Polypodium glycyrrhiza is a FERN growing to 0.5 m (1ft 8in) by 0.5 m (1ft 8in).
It is hardy to zone (UK) 7. The seeds ripen from Nov to March."
"Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil and can tolerate drought." [PFAF]

General: "Evergreen or summer deciduous perennial with a long-creeping, scaly rhizome." [IFBC-E-flora]
Leaves: "Lanceolate, 10-60 cm long, 2-15 cm wide, pinnatifid with sharp deep incisions and elongated pointed segments with toothed margins; rachis with rusty hairs on upper surface in the top one third." [IFBC-E-flora]
Habitat / Range "Dry and seasonally wet rocks, trees, and soil humus in the lowland and montane zones; common in coastal BC; N to SE AK and S to ID and CA, disjunct in AZ." [IFBC-E-flora]

Origin Status: Native [E-flora]

Ecological Indicator Information
"A shade-intolerant, submontane to montane, Asian and Pacific North American fem. Occurs in maritime to submaritime cool mesothermal climates on very shallow, calcium­rich soils; its occurrence decreases with increasing continentality and elevation. Scattered to plentiful in open-canopy forests on water-shedding and water-receiving sites. In­habits exposed soils, coarse fragments (boulders), or cliffs affected by temporary surface flow of water and/or fine or­ganic materials. Common on the calcium-rich bark of broad-leaved trees, typically on Acer macrophyllum. Characteristic of mesothermal forests.(IPBC)" [E-flora]


"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]." [PFAF]


"The rhizome of this fern was and is widely used to flavor Hudson's Bay tea (Ledum groenlandicum Oeder). It is also used for coughs and sore throat." [Norton KaigHaida]

Edible Uses

"Root - raw or cooked[257] The root is sweetly liquorice-flavoured but is thin and fibrous and virtually inedible[200]. The root was commonly chewed for its very pleasant flavour by many native North American Indian tribes[256, 257]. It was often used as an appetiser, especially for children who would not eat[256]. Apart from its used as a pleasantly flavoured chew, it was seen as a famine food and was only used when there was a shortage of better foods[177, 257]."[PFAF]

Medicinal Uses

"Liquorice fern was employed medicinally by several native North American Indian tribes who used it especially as a treatment for a variety of chest complaints[257]. It is little, if at all, used in modern herbalism." [PFAF]



Polypodosides A (59) and B (60) were isolated from the rhizomes of North American fern Polypodium glycyrrhiza DC. Eaton (Polypodiaceae) as additional highly sweet steroidal glycosides [88,89,91]. Polypodoside A (59) shows a high sweetness potency and was rated as 600 times sweeter than sucrose [88,89]. [Rahman SINPC]

Nutritional Information


"Tolerates short periods of drought and direct sunlight, but it prefers bright filtered light[200]. Plants can be grown on a drystone wall[200]. Members of this genus are rarely if ever troubled by browsing deer[233]. There are several named varieties selected for their ornamental value[200]. ..." [PFAF]


"Spores - best sown as soon as ripe 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 in spring[200]."[PFAF]


Polypodium Sp. - Polypody

"Rhizome long-creeping; scales lanceolate, generally ± brown, 1-colored or often with darker central area or midstripe. Leaf: 0.2–10(20) dm, ± alike or fertile > sterile; stipe glabrous to scaly; blade 1-pinnate to generally deeply pinnately lobed (or simple, unlobed), hairy to not, glandular or not, scales on abaxial midrib near base generally lanceolate or lance-linear, generally ± brown; veins free to fused. Sporangia: sori in 1 row on each side of segment midrib, generally raised, sometimes including sporangium-like structures, shriveled sporangia, or branched or unbranched glandular hairs; spores yellow."
"± 40 species: generally New World, temperate, tropics, few boreal. (Latin: many feet, from persistent petiole bases) [Hildebrand et al. 2002 Amer Fern J 92:214–228] Identification complicated in California by fact that 2 or more co-occurring species often hybridize (often indicated by malformed spores), especially in Central Coast (especially Point Reyes), North Coast, where the sterile hybrids may outnumber the parental species, and because coastal ecotypes of several species often have thicker, more succulent blades than inland forms. Polypodium australe Fée except (dubiously reported from but not persisting on San Clemente Island)."[Jepson]

Local Species;

  1. Polypodium amorphum - irregular polypody [E-flora]
  2. Polypodium glycyrrhiza - licorice fern [E-flora][TSFTK]
  3. Polypodium hesperium - western polypody [E-flora][TSFTK]
  4. Polypodium scouleri - leathery polypody [E-flora][TSFTK]

Polypodium spp. (polypody); Polypodiaceae—woods, particularly on rocks or old trees, widespread in northern hemisphere; rhizome eaten raw or added as sweetener; they have a high sugar content; being the sweetest "root" of the northern hemisphere; used e.g., in Italy, Poland, Slovakia, Norway, Balkans, as well as on the western coast of North America.[ETWP]

Polypodium amorphum - Irregular polypody

Family: - Polypodiaceae Family

Polypodium hesperium - western polypody

Family: - Polypodiaceae Family

Leathery Polypody - Polypodium scouleri

Family: - Polypodiaceae Family

Habitat / Range
"Mesic to moist oceanside rock cliffs and trunks and branches of trees (in the salt spray zone) in the lowland zone; frequent on outer coast of Vancouver Island, rare northward to the southern tip of the Queen Charlotte Islands; S to CA." [IFBC-E-flora]4

Origin Status: Native [E-flora]4

""General: Evergreen perennial arising from a thick, smooth, naked, white rhizome."" [IFBC-E-flora]4
""Leaves: Oblong or triangular, 5-60 cm long, 2-15 cm wide, leathery, irregularly pinnately cleft with wide sinuses; leaf margins entire or sparsely finely toothed."" [IFBC-E-flora]
""Notes: In the Barkley Sound area this species hybridizes with P. glycyrrhiza."" [IFBC-E-flora]4

Ecological Indicator Information
"A shade-intolerant, submontane to montane. Pacific North American fem. Occurs in hypermaritime to maritime wet cool mesothermal climates on very shallow soils; its occurrence decreases with increasing elevation and continentality. Common in ocean spray­affected (littoral), open-canopy forests in the proximity of the Pacific Ocean. As does P. glycyrrhiza. P. scouleri inhabits exposed mineral soils, coarse fragments (boulders), and cliffs affected by temporary surface flow of water and fine organic materials. Common on stems and branches of trees, typically on Picea sitchensis. Characteristic of hypermaritime mesothermal forests.(IPBC)"[E-flora]4

Other Polypodium Sp. (non-local)

(Polypodium vulgare) "...the rhizomes have a strong licorice taste, and were once used as a sugar substitute (Turner & Bell). In Scotland, it was made into a medicine for catarrh (Beith), but it was also used for chest complaints, including tuberculosis (Quelch).... If this is what is meant by “pollypodden”, it was used in Ireland for burns. The procedure was to boil the stems with butter. The green juice sets to a jelly, and this is put on the burn (Maloney)." [DPL Watts]


Page last modified on Wednesday, January 12, 2022 6:49 AM