Native Plant of the Month: Sword Fern

Polystichum munitum

Sword ferns are one of the Pacific Northwest’s most iconic species. They are native to the west coast and infamously difficult to grow outside of their natural range. Huge fronds radiate from a central base and each leaflet has a tiny hilt that give the sword fern its name.  

These plants establish themselves in rocky soil but develop to maturity in the acidic, humus-rich soil that characterizes a conifer forest’s understory. The sword fern is also remarkably long-lived; these bushy shrubs survive for 500 years or more. 

Unfortunately, sword ferns around the Puget Sound are dying off and scientists cannot yet identify a cause. In Seward Park within the heart of Seattle, 3% of the sword ferns died in 2015. By 2016, that number had increased ten-fold to a 33% die-off. This alarming trend remains unexplained and six separate locations around the Puget Sound have been affected.  

The humble sword fern offers so much to the Puget Sound region – habitat, relief from stinging nettle, and great soil stabilization. Show this native plant some love this season and take notice of the sword ferns along the Boardwalk Trail or your next hike!

Want to learn more about this topic?

Washington Native Plant Society: Sword Ferns

KUOW: Sword Fern Mystery 

King 5: Massive Fern Die-off