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Native Plant Propagation Guidelines:
ferns & allies

Polypodium glycyrrhiza (licorice fern)

Category: 
ferns and allies

(photo by Dave Polster)

Small to medium sized evergreen fern to 70 cm tall (but often much smaller). Fronds grow from creeping, reddish-brown, scaly, licorice-flavoured rhizomes. Stipes straw-coloured, smooth, usually shorter than the blades. Blades to 50 cm long, once-pinnate; leaflets usually longer than 3 cm, with pointed tips and finely scalloped or toothed margins. Sori oval to round, with no indusium, in a single row on each side of the main vein (Pojar and MacKinnon, 1994). Photo by Dave Polster.

Scientific Name: 

Polypodium glycyrrhiza D.C. Eaton (P. vulgare L. var. occidentale Hook., P. occidentale [Hook.] Maxon)

Family: 
Polypodiaceae
English Name: 
licorice fern

Geographical Range and Habitat Requirements

Ecological Setting: 

On wet mossy ground, logs and rocks (sometimes forms large sheets over rock slabs). Also common as an epiphyte on the trunks and branches of broad-leafed trees (especially bigleaf maple). Coastal BC, Washington and Oregon (Pojar and MacKinnon, 1994; Klinka et al., 1989).

Soil Texture: 

Shallow humic or rocky soils to rock faces.

Nutrients: 

Prefers calcium-rich substrates.

Soil Reaction and Salinity: 

Mildly acidic to moderately calcareous.

Moisture Regime: 

Moist to dry. Poikilohydric ability (curls and dries like mosses and lichens until moisture returns) (Pojar and MacKinnon 1994; Klinka et al., 1989; Vitt et al., 1998).

Shade Tolerance: 

Shade intolerant (Klinka et al., 1989).

Successional Status: 

Unknown. Assume late seral to climax depending on site (Klinka et al., 1989).

BEC Zone and GOE Community Status: 

Dominant species in peripheral Garry oak communities in moister regimes on very shallow rocky soils (Romer, 1993).

Uses

Site Rehabilitation: 

De-vegetated rocky sites and banks.

Wildlife: 

Epiphytic flora like licorice fern is important because it is a habitat niche for organisms. Licorice fern provides food for herbivorous insects and mammals (Nelson).

Landscaping: 

Useful and attractive rock garden plant and areas where winter greenery and ground cover is desired (Brickell et al., 1997).

First Nations: 

Some Aboriginal peoples chewed the sweet rhizomes for the flavour. Some groups ate the rhizomes steamed or broiled. Important medicine for colds and sore throats. They were also mixed with bitter medicines as a sweetener (Pojar and MacKinnon, 1994)

Other Uses: 
n/a

Seed Propagation

Flowering Time: 
n/a
Fruit Ripening Time: 
n/a
Seed Collection Time: 

Late fall and spring

Crop Intervals: 

Annual

Number of Seeds per Kilogram: 
n/a
Seed Viability: 

Highly variable

Fruit and Seed Collection and Extraction: 

When ripe, spores will appear plump and red-brown to cinnamon-brown in colour. Cut fronds from the plant and place, sporangia side down, on a sheet of white shiny paper. Enclose this sheet in newspaper and place in a warm dry place until a fine brown powder can be seen on the paper. Collected spores can then be placed in a container, envelope or jar and placed in refrigerator.

Seed Storage: 

It is best to store spores at 4º C in an air-tight screw-capped vial. For the spore to germinate, it must be kept moist at all times. With increasing spore age, the percentage of viable spores decreases, with an increasing delay in germination. Immediately after collection, spores germinated at about 89.6%, while after four years of storage, germination declined to 53.7% (Kaczynski, 2005).

Fruit/Seed Dormancy and Treatment: 

Spores do not need dormancy breaking, and can be sown as soon as they are ripe (Kaczynski, 2005).

Vegetative Propagation

Method Success Rate Time of Collection
Softwood cuttings    
Semi-hardwood cuttings    
Hardwood cuttings    
Root cuttings    
Suckers    
Plant division Good Spring

 

Outplanting Characteristics and Requirements

As mentioned before, wait until the plants are about two years old before planting out, and make sure they are placed in a shady area which will receive sufficient moisture. Water often enough, depending on climate, but do not saturate. Keep the plant moist at all times, especially during establishment period. While P. glycyrrhiza tolerates drought, it will not survive for long. This plant normally dries in the summer during its dormancy. P. glycyrrhiza grows to 0.3 m by 0.3 m. Height 10-40 cm and spread 40-50 cm. Growth rate and overall lifespan are undetermined (Kaczynski, 2005).

Seed and Cutting Propagation Techniques

Collect and propagate using divisions and spores. Division would be the simplest form of propagation. However, if that is not possible, propagate using spores. Use division in the spring. In summer, the fern goes dormant and can be difficult to find, so mark your plants to avoid destroying them if you will be modifying the site then. Collect spores in the late fall and spring. Sow spores thinly in pots covered with glass or plastic (an aquarium with a glass cover will work to create a moist, humid environment, allowing the gametophytes to fertilize), then carefully place small clumps of the plantlets into individual pots and keep humid. Sow in high densities on the surface of a humus rich, sterilized soil – this plant does not tolerate heavy clay soils or soils that lack sufficient nutrients. Any fairly porous medium such as peat moss, equal parts sand and shredded organic material is suitable. Plant in a sheltered position when plants are two years old. Make sure your plants do not get moldy when under plastic or glass (Kaczynski, 2005).

Additional Information and Photos

For more information and pictures, visit the E-Flora BC website at www.eflora.bc.ca.

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