Western sword fern
The knee-high fern that carpets the Northwest rainforest floor in deep green all year, each leaflet marked with a little hilt like a tiny sword.
Western sword fern at a glance
Polystichum munitum Polystichum munitum is pol-ISS-tih-kum myoo-NY-tum
- Type
- Plant · fern
- Diet
- Producer
- Size
- About knee to waist high, with fronds up to roughly 4 feet long, in wide spreading clumps.
- Lifespan
- A perennial that keeps its green fronds all year and lives many years from the same crown.
- Conservation
- Not formally assessed by IUCN; abundant in Pacific Northwest forests
A green plant that makes its own food from sunlight, thriving in the deep shade of the rainforest floor. It reproduces not by seeds or flowers but by dust-fine spores on the backs of its leaves.
Is it safe to touch?
Harmless. Turn a frond over to find the rows of round rusty-orange dots on the underside, which are the spore cases, and look at the small notch, or hilt, at the base of each leaflet that gives the sword fern its name.
The green floor of the Hoh rainforest at Olympic is mostly one plant, repeated a million times. Western sword fern grows in knee-high clumps so dense and so widespread that they roll out beneath the huge trees like carpet, fronds arching in every direction, deep green in a place where deep green is the whole world. It is the plant your hand brushes on both sides of the trail, and it hides a small joke in its name that you can only get by looking closely.
Kneel and run a finger along a single frond, out past a dozen of its narrow leaflets. Each leaflet, where it joins the central stem, has a tiny bump sticking up at its base, a little notch shaped exactly like the hilt of a sword below its blade. Every leaflet on every frond wears one. Once you have seen the hilts you cannot unsee them, a thousand tiny swords laid out along each leaf, which is how the fern got its name.
Turn the frond over for the last secret. A fern grows no flower and drops no seed. Instead the underside of the leaf carries neat rows of round rusty-orange dots, and each dot is a case packed with spores fine as dust, which puff off and drift away to start new ferns in the wet shade. Because the sword fern holds its green fronds straight through winter, it is often the brightest living thing left on the cold forest floor, which is why the peoples of this coast lined their cooking pits and baskets with it, keeping something green close at hand through the wettest months.
Did you know?
- Each little leaflet has a small bump or notch at its base shaped like the hilt of a sword, which is where the fern gets its name.
- It has no flowers and makes no seeds. Instead it releases dust-fine spores from rows of rusty dots on the undersides of its leaves.
- It stays green straight through winter, so in the cold months it is one of the few bright green plants left on the rainforest floor, and Northwest peoples used the fronds to line cooking pits and storage baskets.
Common questions
Why is it called a sword fern?
Because each small leaflet has a little bump or notch at its base shaped like the hilt of a sword. Once you spot the hilts, they are easy to see all along the frond.
How do ferns make new ferns without seeds?
With spores. Turn over a frond and you'll see rows of round rusty dots. Those release dust-fine spores that drift off and grow into new ferns in damp ground.
Is the sword fern green all winter?
Yes. It keeps its fronds through the cold months, so in winter it is one of the few bright green plants carpeting the forest floor.