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Fern Guide

A Quick Guide to Common Ferns of the Wild Gardens of Acadia

Ferns are among the loveliest types of plants of the Wild Gardens of Acadia. However, few people appreciate the variety found in the group, because they tend to look very similar to the untrained eye. This simplified guide presents the nine most easily identified ferns found in the Wild Gardens of Acadia. Use this guide for some “quick learning” along the Fern Path, and this can propel you into more detailed fern guidebooks! Note that Latin names are sometimes a key to prominent features.

The ferns shown in this guide can be found primarily along the Fern Walk in the Mixed Woods habitat. They can also be seen throughout Acadia National Park. Please remember that all plants in Acadia National Park are protected. Check with your local nursery to find out what native plants are available in your area.

View guide as PDF [3 MB]

Jump to:
Cinnamon Fern
Interrupted Fern
Royal Fern
Long (or Narrow) Beech Fern
Oak Fern
Common (or Rock) Polypody
Sensitive Fern
Bracken Fern
Christmas Fern

Quick Glossary
Frond – the prominent main stem (stalk) and blade of ferns
Pinnae – the smaller leaflets attached (either directly or by a small stalk) to the stem

The “Biggies”

Cinnamon Fern (Osmundastrum cinnamomeum)

Cinnamon Fern
• Key feature: the “cinnamon stick” fertile frond
• Size: 1–5 ft.
• Habit: pointed fronds erect in a vase-shaped cluster, wooly tufts at base of pinnae

Interrupted Fern (Osmunda claytoniana)

Interrupted Fern
• Key feature: crinkly fertile pinnae “interrupt” the frond
• Size: 1–5 ft.
• Habit: vase-shaped cluster of erect fronds, pinnae with blunt tips, no wooly tufts

Royal Fern (Osmunda regalis var. spectabilis)

Royal Fern
• Key feature: has the appearance (and size, when mature) of a small shrub
• Size: 1–5 ft. and even taller
• Habit: large circular cluster of fronds with widely spaced pinnae (like a pea plant)

Smaller Ferns

Long (or Narrow) Beech Fern (Phegopteris connectilis)

Long Beech Fern
• Key feature: lowest pinnae turned down (“britches”)
• Size: 6–14 in.
• Habit: fronds triangular with rapidly tapering tips, pinnae with a direct, webbed attachment to the stem (“connectilis”)

Oak Fern (Gymnocarpium dryopteris)

Oak Fern
• Key feature: black or darkened stem; small and delicate with 3-part frond facing the sky
• Size: 6–18 in.
• Habit: has the appearance of a small and delicate bracken fern

Common (or Rock) Polypody (Polypodium virginianum)

Common Rock Polypody
• Key feature: quite small and growing like a mat on rocks
• Size: 4–15 in.
• Habit: frond widest in middle, pinnae are not divided

Other Prominent Ferns

Sensitive Fern (Onoclea sensibilis)

Sensitive Fern
• Key feature: fronds deeply lobed and cut almost to the stem
• Size: 1–3 ft.
• Habit: temperature sensitive and therefore late to appear & early to fade, triangular frond with a separate beaded fertile stalk

Bracken Fern (Pteridium aquilinum)

Bracken Fern
• Key feature: frond divided into three parts at the top of a long stalk
• Size: 3 ft.
• Habit: coarse and tough triangular fronds relaxed and facing the sky

Christmas Fern (Polystichum acrostichoides)

Christmas Fern
• Key feature: evergreen pinnae look like “Santa’s boots”
• Size: 8–24 in.
• Habit: dark green fronds in a vase-shaped clump tapering near the tip, upper pinnae of fertile fronds quite small


The Quick Guide to the Common Ferns of the Wild Gardens of Acadia was created by Leah Rae Donahue, Mary Ann Handel, and Pam Parvin, and produced with the expertise and knowledge of the Wild Gardens volunteers and the Master Gardener Volunteer program of the University of Maine Cooperative Extension. For more information on the Master Gardeners program, visit