A Winter Treat: Licorice Fern (Polypodium glycyrrhiza)

Licorice fern (Polypodium glycyrrhiza)

When many Northwest ferns have said adiós to most of their aboveground growth and have nearly left the stage, enter licorice fern. If you have it in your yard you might forget it’s there until the soft rains of autumn release it from its dormancy. Then—when you least expect it—bright green, featherlike fronds (to about 12 inches) gradually appear to help brighten the landscape all winter long. Although licorice fern may stay evergreen where it is well established, out of harsh sunlight, and receives some moisture in the form of mist or from a watering can, it is typically a summer deciduous plant. It is a primary producer for other inhabitants within the ecosystem, including insects, birds, and other animals.

Its botanical name, Polypodium glycyrrhiza, means “many footed” and “sweet root,” and refers to creeping rhizomes that taste like licorice (which I’ve yet to try). Native Americans used the rhizome to sweeten foods and unpalatable medicines, but they also used it as medicine itself, to treat sore throats and upper respiratory infections. Modern herbalists use it for similar purposes.

How it grows Licorice fern on American elm
Licorice fern is one of those multitalented plants that occurs naturally in several habitats. The next time you walk under a
massive, mature deciduous native tree like big-leaf maple or even a nonnative giant, such as American elm (native to the eastern U.S.), look upwards and there’s a good chance you’ll find it growing as an epiphyte on trunk and branch bark, particularly in crotches or on horizontal limbs that usually stay wetter than vertical ones. But it’s also found growing on dead or dying wood like logs and stumps, and as a lithophyte in rocky outcrops and mossy ledges (pictured, below).

Licorice fern (Polypodium glycyrrhiza)

 

 

 

Licorice fern occurs naturally in cooler parts of the Pacific Northwest (west of the Cascades) and near the California coast (as well as small sections of the Sierra Nevada), at low elevations. Disjunct populations in Idaho and Arizona are listed as imperiled.

 

Rescue mission
The ferns that now grace my yard were rescued from mature street trees that had the misfortune of being cut down or blown down in my neighborhood. The trees’ upper branches were nearly covered with the ferns, so when the fallen limbs were in the street awaiting transport, I peeled off  bark adorned with the featherlike fronds, their roots firmly and securely attached to the bark. I placed sections of the leafy mats under native shrubs and in shaded rocky areas in my yard, where the soil is fairly rich and slightly acidic, and where moss grows readily (and not too far from the hose, since I figured they would need to be kept moist for a couple of summers). Or, I placed some logs, leftover from fruit tree prunings, under or immediately next to those without the company of rocks. Now the mats have come to life again, and I think they are quite settled in, judging by a new little plant that’s appeared about 10 feet from its parents—spores are in the air!

Licorice fern (Polypodium glycyrrhiza)Try it at home
If you’d like to try growing licorice fern in your yard, pick a spot that’s naturally mossy, since most areas that support moss ought to be able to support this fern. And be sure that you can get to it easily with a watering can while the plants are young; they will need to be kept moist—but not saturated—until they’re established, at which time they will become self-sufficient (except during exceptionally hot periods when dormant plants will appreciate an occasional splash of water).

If moss isn’t growing in your garden, try nestling a plant between shaded, half-buried rocks that have been enhanced with a slightly acidic, humusy and well-draining soil amendment like leaf mold. Or, try licorice fern’s close relation, Polypodium hesperium—it can take drier conditions and grows naturally in rocky places on both sides of the Cascades. Its short stature makes it a lovely addition to nooks and crannies of stone walls, as well as a candidate for creeping through a mostly shaded rock garden. Licorice fern’s other Northwest relative, P. scouleri, is a leathery-leaved gem that grows along the foggy coastline from British Columbia, south into California. But it is reportedly difficult to cultivate so should just be left alone to bask in the ocean’s salty mist.

As always, buy all native plants from reputable nurseries and never harvest from the wild. Or, rescue them from doomed situations, preferably at a time that will benefit the transition.

© 2015 Eileen M. Stark

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