Yesterday I attended a guided walk within Mt. Toby State Forest, with the goal of finding, and learning about, as many species of fern as possible. Due to the varied habitats, soil types, and pH measurements (an important environmental component for ferns) found throughout Mt. Toby State Forest, there is exceptional fern diversity at this location. All told, we found 23 species of fern (listed below), with at least 3 others likely present at the site.

Fern identification can be facilitated by focusing on a few key characteristics, such as number of leaf divisions, growth form, and the shape, size and placement of the spore producing structures. As such, I have grouped the descriptions below by the number of leaf divisions, and included some notes on the growth habits and spore producing structures of each species. We covered more about these species than I could possibly include here, but for now I will include a fun fact or two with each species below.

 

Undivided

1. Walking Fern (Asplenium rhizophyllum) 

Growth habit: Spreading

Spore producing structure: Sori elongate; underside of leaves

Fun facts: Many of the leaves end in long skinny extensions that can sprout new ferns from the tips where they touch the ground. These ferns are relatively rare since they prefer to grow on exposed, moss-covered limestone boulders.

 

Once divided

2. Maidenhair Spleenwort (Asplenium trichomanes)

Growth habit: Clumping

Spore producing structure: Sori relatively large, oval-shaped, typically four to each sub-leaflet.

Fun fact: Often found growing in nooks and crannies of rocky cliffs.

 

3. Narrow-leaved Glade Fern (Diplazium pycnocarpon)

Growth habit: Spreading

Spore producing structure: Sori elongate; chevron-type pattern underside of narrower leaflets on erect fertile frond (other leaves arc downwards).

 

4. Sensitive Fern (Onoclea sensibilis)

Growth habit: Spreading

Spore producing structure: Separate fertile frond; sori clustered like beads

 

5. Rock Cap Fern (Polypodium appalachianum / Polypodium virginanum)

Growth habit: Spreading

Spore producing structure: Large, round, bright colored sori on the undersides of leaves

Fun facts: As the name suggests, it grows on top of rocks. The two species, P. appalachianum and P. virginianum, differ in their number of chromosomes. P. virginianum is tetraploid (possessing four homologous sets of chromosomes), while P. appalachianum is diploid (two complete sets of chromosomes – one from each parent). To confuse matters, they can hybridize, which produces triploid individuals.

 

6. Christmas Fern (Polystichum acrostichoides)

Growth habit: Clumping

Spore producing structure: Undersides of leaflets are almost covered by sori.

Fun facts: Christmas ferns are evergreen; leaf fronds remain largely vertical until after leafdrop, and then start to droop. In this way they can remain on top of the dried leaves to continue photosynthesizing during warm days in the winter.

 

 

Twice divided

7. Silvery Glad Fern (Deparia acrostichoides)

Growth habit: Clumping

Spore producing structure: Sori elongate; herring bone pattern.

Fun fact: Silvery hairs at the base of the stem can help in identification.

 

8. Goldie’s Fern (Dryopteris goldiana)

Growth habit: Clumping

Spore producing structure: Rows of small round sori on the undersides of leaflets.

Fun fact: The fiddleheads are covered with a golden fur when they emerge in the spring.

 

9. Marginal Wood Fern (Dryopteris marginalis)

Growth habit: Clumping

Spore producing structure: Small round sori at margins of leaflets.

 

10. Ostrich Fern (Matteuccia struthiopteris)

Growth habit: Clumping/Spreading

Spore producing structure: Separate fertile frond, which persists through the winter

Fun fact: Deeply grooved stem can help in identification. Fiddleheads of the ostrich fern are edible.

 

11. Interrupted Fern (Osmunda claytoniana)

Growth habit: Clumping

Spore producing structure:  Spore producing leaflets “interrupt” non-spore bearing leaflets in the center of the main stem.

Fun fact: Similar in appearance to the Cinnamon Fern, but lacks the “hairy tufts” at the base of leaflets that are present on Cinnamon Ferns.

 

12. Cinnamon Fern (Osmundastrum cinnamomeum)

Growth habit: Clumping

Spore producing structure: Separate fertile frond appears in May

Fun fact: In early spring, both the fiddleheads, as well as the base of the stems on newly emerged leaves, are covered in fuzz. Hummingbirds collect this material to line their nests.

 

13. New York Fern (Parathelypteris noveboracensis)

Growth habit: Spreading

Spore producing structure: Horseshoe shaped sori on the undersides of leaflets.

Fun fact: The overall leaf shape tapers at both ends. A helpful pneumonic for remembering how to identify New York Ferns: “New Yorkers burn the candle at both ends.”

 

14. Long Beech Fern (Phegopteris connectilis)

Growth habit: Spreading

Spore producing structure: Small sori on undersides of leaflets

Fun fact: Similar growth pattern to the Broad Beech Fern – long stem, bottom leaflets pointed forward, and leaflets oriented horizontally (i.e., parallel to the ground).

 

 

Thrice divided

15. Maidenhair Fern (Adiantum pedatum)

Growth habit: Spreading

Spore producing structure: Has a membrane under the leaflets that cover the sori.

Fun fact: Circular frond arrangement.

 

16. Lady Fern (Athyrium angustum)

Growth habit: Clumping

Spore producing structure: Long, somewhat curved sori (i.e., comma shaped)

Fun fact: Black hair-like scales on lower stem can help with identification.

 

17. Bulbet Fern (Cystopteris bulbifera)

Growth habit: Clumping

Spore producing structure: Extremely small sori on the undersides of leaflets.

Fun fact: The Bulbet Fern is so named due to the small bulb-like buds produced on the underside of the main stem, which drop off in the fall. At favorable locations, these fallen bulblets develop into small ferns.

 

18. Hay Scented Fern (Dennstaedtia punctiloba)

Growth habit: Spreading

Spore producing structure: Sori arranged along the margins of the undersides of the leaflets.

Fun fact: The main stem has tiny glandular hairs, which creates a somewhat sticky feel to the leaf, as well as produces an aromatic scent.

 

19. Spinulose Wood Fern (Dryopteris carthusiana)

Growth habit: Clumping

Spore producing structure: Round sori on the undersides of leaflets.

Fun fact: Can be distinguished from the Intermediate Wood Fern because in the Spinulose Wood Fern, the sub-leaflets closest to the main stem are the longest of that leaflet, while in the Intermediate Wood Fern, the sub-leaflets closest to the main stem are shorter then the next sub-leaflets.

 

20. Intermediate Wood Fern (Dryopteris intermedia)

Growth habit: Clumping

Spore producing structure: Round sori on the undersides of leaflets.

Fun fact: Although the leaves droop to the ground in the winter, they are evergreen. Having fully formed leaves at the start of the spring allows the Intermediate Fern to capture a great deal of sunlight before the trees leaf-out, shading the ferns below.

 

22. Broad Beech Fern (Phegopteris hexagonoptera)

Growth habit: Spreading

Spore producing structure: Very small sori on the undersides of leaflets.

Fun fact: Similar growth pattern to the Long Beech Fern – long stem, bottom leaflets pointed forward, and leaflets oriented horizontally (i.e., parallel to the ground).

 

23. Bracken Fern (Pteridium aquilinum)

Growth habit: Spreading

Spore producing structure: Sori arranged along the outer margins under leaflets.

Fun fact: Very common fern; has been found on every continent (including fossils found on Antarctica). Easily recognizable by its equilateral triangle shape.