Ferns of the Pacific Northwest

A few folks mentioned that my fiddlehead video was a little too fast (watch it here).  I’ll admit that it was hard to follow.  It was my first video after all.

So as the ferns have unfurled themselves, I thought I might outline how to identify them.  If you get your fern ID down now, fiddlehead ID will be a lot easier next spring.  I’m going to cover the 6 most common ferns in the Pacific Northwest.

First, some definitions


Image Source: Fern Finder: A Guide to Native Ferns of Central and Northeastern United States and Eastern Canada.  Se below for details


Leaf/Frond:  The whole frond of a fern is called the leaf.

Leaflet/Pinna: These branch right off the stem.  You might be tempted to call them a leaf.

Lobe/Pinnule:  not all fern have this. They branch off of the leaflet.

Pinnate: This is the number of times a leaf branches. For example, a sword fern would be once pinnate, because the leaflets that branch from the stem are solid, with nothing branching off of them.

Scales:  The paper-like scaly bits at the bottom of the fern.

Sori:  The little clusters of spores on the undersides of leaflets.  I mention them mostly because in the video, I was calling the scales the sori.  Oops.

sword spore
Sori/spore clusters on undersides of some leaves.







okay, let’s take a look at these ferns...

Sword Fern (Polystichum munitum)

Photo credit: Krzysztof Ziarnek, Kenraiz. See below

Sword fern is by far the most common fern around here.  Its waxy leaves don’t rot over winter, leaving the old fronds from last year battered and clinging to life.  We can think of it as the obnoxious slob of the fern world.

The main feature you need to know is that it is once pinnate and generally large (up to 1.5 m) with plenty of scales.  In summer, the clusters of spores on the undersides of leaflets are easy to find.

The other once pinnate ferns in the area (deer fern and licorice fern) have a few differences.  I’ll get to them in a minute.  The scales of this fern make it unpleasant in fiddlehead form.

Deer Fern (Blechnum spicant)



Deer fern can look a lot like a small sword fern to the untrained eye, but there is one significant difference…at least in the summer.  Deer fern produce two types of fronds.  The sterile ones, which resemble those of sword fern, but are generally narrower and less battered looking.  They stick around all winter, but unlike sword fern fronds, never produce spores.  The spore making is up to the fertile fronds, which stick straight up with skinny little leaflets poking out of the stem. Their undersides will be covered in spores.

The fertile fronds are only around in summer, so if you are IDing ferns in the winter, take time to compare the plants.  The deer fern is a much less obnoxious plant.

Licorice Fern (Polypodium glycyrrhiza)

Photo Credit: Alanah Nasadyk; see below for details.


31719654226_6f5fdc407a_z (1).jpg

Photo Credit: Alanah Nasadyk. See below for details.


Licorice fern may not be a major contender for dominant fern of the PNW, but it is my favourite fern and I did mention it in a video (watch it here).  It is only once pinnate so could be confused with sword fern, but it is much smaller, and usually grows as a single frond, or a group of single fronds, rather than in a bunch.  The other main factor is that the Licorice fern always grows on moss.  It prefers maple trees, but I’ve seen it on mossy ground, rocks, logs, and other species of trees.  The other defining feature is its taste.  Pick a frond and bite the base.  It should taste a little like licorice.  Bite the rhizome (root) and it should taste overwhelming so.  None of the ferns around here are particularly toxic poisonous, so it probably won’t kill you if you get it wrong.  It seems to grow better during the cooler months.

Lady Fern (Athyrium felix-femina)


plant.jpgI would hazard to call this the second most common fern in these parts, often growing alongside sword fern.  True to its name, lady fern is the daintiest of the bunch, though it can grow to a hefty 2 m.  Old fronds from the year before tend to rot before the next batch come out.  The leaves are 2-3 time pinnate and much softer than the other ferns.  The leaflets are smaller at the top and bottom, making them somewhat feather shaped.  The leaflets tend to start fairly close to the ground and the scales at the base are less prominent than the similar looking spiny woods fern (see image below).  Lady fern is the most edible fiddlehead in the PNW.

Spiny Wood Fern (Dryopteris expansa)


dryopteris_expansa_lg.jpgIt’s easy to mistake a spiny wood fern with a lady fern, especially a young lady fern. There are some key differences though.  The leaflets typically start further up the stem, and the bottom ones are the longest.  The result is the frond looking more like a triangle…so they look a little spiny…get it?  They also have more scales around their base, another feature that makes them a little spiny.  Besides that, they are often smaller, growing in poorer soil than lady fern, often on very rotted logs.  This is not always a great indicator though, because they often grow right beside lady fern.

Spiny wood fern (left) has many brown papery scales at its base, considerable less than lady fern (right).  Lady fern stems will also be thicker and lighter in colour.

Bracken Fern (Pteridium aquilium)

Photo credit: Rasbak; see below for details.

Folks often have trouble telling bracken fern apart from spiny woods fern and lady fern. The first thing I’ll say is that they tend to be bigger – up to 5 meters tall, in fact (but usually around 1 or 2).  They like meadows and clearings, rather than the dense forest that lady fern and spiny woodfern prefer.  The main difference that I use, however, the leaflets.  They appear to grow on a stem branching off from the main stem, whereas the leaflets of other ferns look a little more…umm…leafy.   If you were to cut one leaflet off, it would resemble an entire spiny wood frond.

There are other ferns around here, but they are generally smaller and less common, usually growing on cliff sides and out of the way places.  If you are really that into learning more, I would recommend  Lone Pine’s Plants of Coastal British Columbia.  It’ll do for you Washingtonians as well.

Clear as mud, right?  This is the video I keep referring to.  It was my first one, so be gentle.

Photo Credits

Diagram: Illustration derived from Fern Finder: A Guide to Native Ferns of Central and Northeastern United States and Eastern Canada by Anne C. Hallowell and Barbara G. Hallowell, published by Nature Study Guild Publishers

Sword Fern by Krzysztof Ziarnek, Kenraiz [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)%5D, from Wikimedia Commons

Deer fern – public domain

Liquorice fern Alanah Nasadyk; https://www.flickr.com/photos/146378829@N04/31719654226   [CC BY-SA 2.0 CC BY-SA 2.0  (https://creativecommons.org/licenses/by-sa/2.0)%5D

Lady fern by Barry Breckling.  Public Domain from US Forest Service

Spiny Wood Fern: Public domain from US Forest Service

Bracken Fern – Rasback; Rasbak [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)%5D, from Wikimedia Commons https://commons.wikimedia.org/wiki/File:Adelaarsvaren_plant_Pteridium_aquilinum.jpg)]

31719654226_6f5fdc407a_z (1).jpg

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