Not Just Japanese Plants, Part II: Pacific NW Native Ferns in Our Garden
In last month’s article, I discussed shrubs in the Seattle Japanese Garden that are native to the Pacific Northwest. Our garden’s Japanese designer, Juki Iida, chose to include NW natives – even though they’re not found in the gardens of Japan. This decision is consistent with the essential nature of Japanese gardens – that they be “rooted in place,” reflecting the landscape where they’re created. For me, the NW native plants in our garden blend seamlessly with plants native to Japan.
In this article, I’ll consider our garden’s NW native ferns.
Western Sword Fern (Polystichum munitum) is a large evergreen fern native our area, west of the Cascade Mountains – and widespread from British Columbia to Oregon. It grows at low to middle elevations, and is common even in urban areas. I live in the Arbor Heights neighborhood of West Seattle, still noted for its large native trees, and have at least 100 Sword Ferns on my property. I love them, even though they’re not considered “special,” and even though they planted themselves!
Sword fern is a tough and adaptable evergreen, cold hardy to USDA Zone 3. It forms an arching mound of “erect leaves forming a crown from a stout, woody, scaly rhizome.” [Rhizome is the botanical name for an underground stem. This and other quotations are from Plants of the Pacific Northwest Coast, by Pojar & MacKinnon.] Leaves, known as fronds, are erect or arching, lance-shaped, and pointed at their tips, with sharply toothed leaflets.
Western Sword Fern grows to more than 3 feet tall and wide at maturity. Although it does best in moist, well-drained, humus-rich soil in part to full shade, it tolerates less than ideal, wet or dry conditions. It will grow in the dry shade beneath tall native conifers. However, it requires regular watering if grown in our gardens in full sun.
Sword Ferns were used by native peoples for food, medicine, bedding, and in the cooking & storage of food. They were also used in a traditional children’s game called “pala-pala.” This was a competition to see who could pull the most leaflets from a leaf while taking a single breath – at the same time saying “pala” as each leaflet was pulled.
Deer Fern (Blechnum spicant) is a smaller, more delicate-looking native fern. It grows in “moist to wet forests … lowlands to middle or even subalpine elevations.” It’s also evergreen -- and “tufted at the end of a short stout rhizome.” Cold hardy to USDA Zone 5, it matures to about 2 feet tall and wide. Although it grows best in moist, well-drained, humus-rich soils in light to deep shade, and benefits from summer watering in our gardens, it also tolerates sandy and clay soils.
This fern is characterized by two very different kinds of fronds. The sterile fronds (those that don’t produce spores) are evergreen, leathery, about 30 inches long, and often pressed to the ground. The fertile fronds are deciduous and emerge, upright in habit, from the center of the clump. The leaflets are “much narrower … [and] sometimes rolled into near-tubes,” which gives the fronds a wispy appearance.
Traditionally, the leaves were chewed by hunters and travelers to suppress hunger, and were used as a medicine for skin sores. Elders reportedly learned of this use “by watching deer rub their antler stubs on this plant after their antlers had fallen off.”
Licorice Fern (Polypodium glycyrrhiza; also known as P. vulgare) is a small to medium-sized evergreen fern. Its primary range is from southeastern Alaska to California, but it also appears in Idaho and Asia. It grows at low elevations on seasonally wet rocks, logs, trees, and humus-rich soil. It’s commonly an epiphyte (a plant that grows above the ground, usually on another plant, but is not parasitic) on the calcium-rich bark of broad-leaved trees – such as Bigleaf Maple (Acer macrophyllum). Like other epiphytic plants, it provides important habitat for many organisms. It’s also a food source for mammals and insects.
The fronds are lance-shaped and over two feet long, with finely toothed leaflets. They emerge “from a creeping, reddish-brown, scaly, licorice-flavored rhizome.” Polypodium means “many feet” and refers to the plant’s branched rhizomes. Glycyrrhiza comes from the Greek glykys (sweet) and rhiza (a root). The rhizomes are creeping, branching, licorice-flavored and very sweet.
Rhizomes were chewed for their flavor by many native peoples. They were dried, steamed, scorched or eaten raw. They were an important medicine for colds and sore throats, and were also used to sweeten bitter medicines.
Western Maidenhair Fern (Adiantum aleuticum) is a graceful deciduous fern that typically grows 1 ½ to 2 feet tall, and is hardy to USDA Zone 3. It was formerly given the species name of the East-coast native (Adiantum pedatum). In fact, the specimen in our garden was first documented under the latter name. However, there are significant differences visible to observers -- and the East coast species struggles in our area, tending to die out over time.
The Western species has wiry black stipes (leaf stalks) that fork into two distinct branches, creating a “fan” of six to eight finger-like, bright green pinnae (the primary divisions of a compound leaf). The fan is displayed horizontally and measures up to 18 inches across. All pinnae are delicately divided, but the middle one is distinctly longer in length than the others. This, and the number of pinnae, are two characteristics that distinguish it from A. pedatum. Both ferns bring a unique, delicate beauty to nature and to the garden.
Western Maidenhair fern grows best in moist, organic, well-drained soils in light to full shade. In gardens, it requires regular watering during our dry summers. It grows at low to middle elevations, thriving in rocky forests, by streams and in coastal areas. Hikers frequently encounter its ethereal beauty on cliffs and next to waterfalls.
Adiantum aleuticum was used traditionally in basketry and as a medicine to increase strength & endurance. The word maidenhair refers to its delicate hair-like stems – or alternatively, to its fine, dense roots.
In the Seattle Japanese Garden, it’s located near the fence in the garden’s SW corner, on the south side of the stream
A neighbor of mine once commented that “ferns belong in the woods,” as if they should only exist in places where she won’t see them. I find it sad that she doesn’t see the beauty & resilience that ferns bring to nature, here in the Pacific Northwest -- and to the gardens, public and residential, where they’ve arisen or have been planted.
Corinne Kennedy is a Garden Guide, frequent contributor to the Seattle Japanese Garden blog, and retired garden designer.