Ferns of the Acadian Forest Region

A while ago I was inspired by a walk through my neighbourhood to write about the ferns common in my area. With Acadia University’s Native Plant Sale happening in just one month on May 7th, I’d like to expand the scope and explore the broader diversity of ferns in Nova Scotia. There are over 40 native species here, plus a slightly-confounding array of hybrids, so I’ll restrict myself to those more commonly seen around the province and save the rarer ferns for another post.

The Acadian Forest

Nova Scotia and most of the Maritimes lies within the “Acadian Forest Eco-Zone,” an area that also includes parts of northern New England and south-eastern Quebec. The title is an historical reference to “Acadia,” the name for the region before England won it from France in the mid-18th century. As an eco-zone it is made distinct by its intermediate position between the great boreal softwood forests to the north and the hardwood forests that extend southward. It’s a place where northern species of plants and animals are at their southernmost limit and southern species at their northern limit. The whole area is strongly influenced by the moist air and temperate climate provided by the Atlantic Ocean that bounds it to the east. The moist climate and short, cool summers mean extensive forest fires are uncommon, resulting in a tendency towards a complex of mixed-age, old growth forests.Acadian Forest Map

Here near the top of the Appalachian mountain range habitats suitable for alpine and tundra plants meet those of the southern forests and the Atlantic coastal plain. The website of the Harriet Irving Botanical Gardens lists eight main habitat types within the Acadian forest region, including softwood, mixed and deciduous forests, marshes, bogs, sand barrens and salt-sprayed coastal headlands. Like all plants found here, the distribution of ferns is influenced by soil type, moisture availability, elevation and exposure (solar and oceanic). Glaciation has had a significant impact on Nova Scotia’s landscape with many places having thin soils and plenty of glacial till – that means rocky-as-heck! Where I live the underlying rock is granite making for quite acidic growing conditions. In other areas of the province limestone and marble create “sweeter” conditions and provide habitat for lime-lovers. A wonderful mix, and a great place to find a diverse range of ferns. Listed below are some of my favourites.

Ladies First

Athyrium filix-femina ‘Lady in Red’ fern in May spring

Red-Stemmed Lady Fern

The Northern Lady Fern (Athyrium angustum) is a common fern across NS. Look for it in ditches, along woodland edges and other moist places like swamps. Considered by some a sub-species of the European Lady Fern (A. felix-femina), I prefer to keep them separate. Unlike the European variety, ours also has a fairly common, naturally occurring red-stemmed form (forma rubellum) that’s known in the plant trade as “Lady in Red.” The fronds of lady fern are twice pinnate giving it a more delicate look than the wood ferns it sometimes grows along side. The stems are also much less scaly than wood ferns being restricted to the lower parts of the stem below the greenery. This is a useful characteristic for differentiating the two genera and was presented to me in a fern ID class put on by the New England Wild Flower Society in the pneumonic “ladies have hairy legs.” Lady ferns are spreading ferns easily grown in rich soils that never dry out. They do have somewhat brittle stems and so should be sited away from strong winds or trampling kids and pets.

The Wood Ferns

Fancy Wood Fern

Silhouette_spinulose wood

Spinulose Wood Fern

A variety of wood ferns (Dryopteris spp.) are common around NS. I’d say most common are Fancy Wood Fern (D. intermedia) and Spinulose Wood Fern (D. carthusiana). At first glance these two ferns look quite similar. Making identification even more difficult, where they co-habitate they hybridize freely with each other and just about any other wood fern present (naughty!). This creates a complex of intermediate forms sure to confound even the experienced ferner. Don’t let that daunt you; the species themselves are easily differentiated by looking at their lowest set of leaflets. On Fancy Wood Fern the inner-most pinnae closest to the stem are always shorter than those adjacent. With Spinulose Wood Fern it’s the opposite, with the inner-most being longer than those adjacent. These silhouettes were created by the late naturalist Nels Maher. You can see more of his work at the website Ontario Ferns.

Marginal wood fern (D. marginalis) is probably the third most common wood fern I see around NS. A great fern for rocky ground (or even on rocks). It seems to prefer soils that are only slightly acidic to near-neutral because I haven’t found it on the South Shore where I live, but do see it regularly when hiking around the North and South Mountains that rise above the Annapolis Valley. A strongly clumping fern, it has blue-green evergreen foliage that looks good right through the winter. Tolerant of a variety of situations, including some sun, if you’re new to native ferns this is highly recommended starter fern.

The Genus Osmunda

Named for the Saxon god Osmund (aka Thor), although I’m not sure exactly why. This genus is one of the oldest fern genera around being found in fossil records from 200 million years ago. Also some of the longest living ferns, there are three representatives in NS: Cinnamon Fern (O. cinamomea) introduced in an earlier posting “Who are the ferns in your neighbourhood?”, Royal Fern (O. regalis) and Interrupted Fern (O. claytoniana). All are large ferns of moist places. Two distinctive features of this group are their strongly dimorphic forms (separate fertile and sterile fronds on the same plant) and the fact that their spores are green with chlorophyll, which makes them very short lived. This ancient group also doesn’t have the mechanism to catapult their spores that many ferns have, but instead the spore cases just split open to let the spores drift with the wind. See if you can identify which is which in the pictures below.

Osmunda claytoniana

Cinnamon Fern

Osmunda regalis green spore







Holly Ferns

There are two holly ferns (Polystichum spp.) you will see in many places across NS. Christmas fern (P. acrostichoides) is the more widely distributed. Named for its use as a seasonal decorative greenery in times before the floral trade, it is a clumping evergreen fern that’s quite drought tolerant once established. The deep blue-green, once-pinnate leaves offer a bold statement in the woodland garden and a strong contrast to the silvery down that covers the emerging fiddleheads in spring. Christmas fern is very easily grown in part to full shade. Braun’s holly fern (P. braunii) is a robust, luxuriant-looking plant. It’s not as common as its cousin the Christmas Fern, likely due to it’s need for a moist soil of neutral pH. That said, it’s easily found in places like Blomidon Provincial Park and in the Cobequid Mountains of north-central NS. It’s an awesome sight to see it growing in beautiful association with our native foamflower, Tiarella cordifolia.

A Selection of Moisture-Loving Groundcovers

Wild Combo 3

Oak Fern

While the summers in the Acadian Forest Region are described as moist and cool, our rocky woodlands can be quite dry at that time of year. Where moisture is assured all season several ferns are likely to set-up home. All the ferns described here are colonizing and can make great carpeting groundcovers on the forest floor or along shaded streams and rivers. Oak fern (Gymnocarpium dryopteris) is a tiny fern. Looking like a miniature Bracken Fern (Pteridium aquilinum), although without the thuggish demeanor, it looks ever-so-sweet meandering through carpets of star flower (Lysimachia borealis), bunchberry (Cornus canadensis) and bluebead lily (Clintonia borealis). It’s also one of the first ferns I had success reproducing from spore, albeit in its plumose form.

Another small fern that makes a useful blanket for persistently moist areas is New York Fern (Thelypteris noveboracensis). It’s bright apple-green colour really lights up shady wet spots where other plants struggle. Finally, if space is no issue, Ostrich Fern (Matteuccia

struthiopteris) is THE pick. This is our edible fiddlehead (and largest agricultural export in our neighbouring province of New Brunswick – who knew?) At up to 4-5 feet

Matteuccia struthiopteris_Frond

Ostrich Fern makes a beautiful vase-shape

this fern can create quite a tropical effect. It will grow quite happily in partly shaded and evenly moist garden soil, but if given ample moisture can tolerate full sun, at least here in coolish NS. Be aware that while the crowns appear strongly clumping, that single fern in the pot you buy will send out runners and in short order you’ll have a colony. However, unlike many other super-assertive plants, this one you can just eat if it gets out of hand – a rather delicious dilemma 😉

And that’s just a taste of the amazing fern diversity in Nova Scotia!