Polypodium glycyrrhiza, commonly known as licorice fern, many-footed fern, and sweet root, is an evergreen fern native to western North America, primarily in a narrow strip in southern Alaska, southwestern Yukon Territory, western British Columbia, Washington, Oregon, and California, though two highly disjunct populations are known from Idaho and Arizona. It thrives in a humid climate, prevailing in areas with cool and moist summers and warm and wet winters. P. glycyrrhiza can often be found growing on the trunks and branches of deciduous trees, particularly bigleaf maple, but is also often found on rocks, logs, and wet, mossy humus. Habitat elevation is lowlands below 600 meters.
Licorice fern acquires its name from its licorice-flavored rhizome, which was chewed for flavor by numerous Native American groups, including the Sḵwx̱wú7mesh, Shishalh, Comox, Nuxalk, Haida, and Kwakwaka'wakw. The rhizomes were also usually used medicinally as a treatment for the cold and sore throats. 
Spores are located in rounded sori on the undersides of the fronds, and are released in cool weather and high humidity.
This species is a diploid, and is one parent of several species of hybrid origin:
- Polypodium vulgare (with Polypodium appalachianum)
- Polypodium hesperium (with Polypodium amorphum)
- Polypodium calirhiza (with Polypodium californicum)
This species is in cultivation, and the cultivar 'Longicaudatum' has gained the Royal Horticultural Society's Award of Garden Merit. It is not as rock-dependent as are many related species. A hybrid between this species and Polypodium californicum has been named Polypodium calirhiza and is in cultivation.
- Pojar, Jim (2004). Plants of the Pacific Northwest Coast. Edmonton: Lone Pine Publishing. ISBN 978-1-55105-530-5.
- "RHS Plant Selector - Polypodium glycyrrhiza 'Longicaudatum'". Retrieved 28 May 2013.
|Wikimedia Commons has media related to Polypodium glycyrrhiza.|
- Jepson Manual Treatment - Polypodium glycyrrhiza
- USDA Plants Profile: Polypodium glycyrrhiza
- Flora of North America
- Washington Burke Museum
- Polypodium glycyrrhiza - U.C. Photo gallery
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