Plant Talk with Sweet Fern

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Aromatherapy’s Global and Local Aromatics

Over the years, the practice of Aromatherapy has led me down a path of meeting and working with several aromatic plants and their respective essential oils from around the globe. This includes some of the usual “essential oil suspects” such as Tea tree, Eucalyptus, Lavender and Frankincense that are now relatively easy to find in health food stores, local drug stores and on the Internet. Yet over time it struck me how aromatherapy and essential oil literature focuses on plants that aren’t from North America. Heck, even aromatic plants that we focus on for landscaping and herb gardens are often the ones from the Mediterranean basin such as Lavender, Thyme and Oregano. Interesting, right?

A closeup of Sweet Fern growing on Long Island's northern coastal bluffs.

Highlighting North America’s Aromatic Sweet Fern

There are several aromatic plants endemic to North America to know and enjoy such as Monarda fistulosa, Goldenrod, Pinyon Pine and Eastern Red Cedar and one friend I have been slowly getting to know over the past few years named Sweet Fern (Comptonia peregrina). The aromatic plant world of North America beckons! This article and video (!) take you on a brief journey of Sweet Fern’s story including growing preferences and its herbal and aromatherapeutic applications.

Not A Fern but Resembles One

Oh, what’s in a name? Sweet Fern suffers from what I like to call a nomenclature identity crisis as it has no relation to actual ferns and is incredibly aromatic, which is unlike nearly all ferns! As an aside: the only aromatic fern I know of is Dryopteris fragrans (Fragrant Fern) which I learned about from “The Fern Lover’s Companion” by George Henry Tilton. But back to Sweet Fern. I never knew about this plant until I was looking for native plants of the Long Island Sound region to help prevent soil erosion on an area of land near a costal bluff. Sweet Fern came up during my research and it has been a love affair ever since! The young plants I introduced to the area of concern have thrived and colonized the area, happily getting along with Blue star (Amsonia hubrichtii) and Bayberry (Myrica pensylvanica).

Close up of Sweet Fern with an actual Fern taken in mid-November.
Sweet Fern (red-bronze) in mid-November with Blue Star (yellow) on the left and Lady fern (still green!) peeking through.

Sweet Fern Nomenclature

If you are looking to know and purchase Sweet Fern, it is also called Liquidambar peregrina and Liquidambar aspleni folia. These common names are based off of the Latin name of the plant, which is Comptonia peregrina. Botanists often disagree about classification over the years, so you may also see references to Myrica asplenifolia and Comptonia asplenifolia. Regardless, you know Sweet Fern when you see and smell it nearby!

Thanks to the Missouri Botanical Garden, I came to learn that the Genus is named after Henry Compton (1632-1713) who was a Bishop of London, dendrologist and patron of botany. The epithet “peregrina” references roaming, traveling or living abroad, which I feel nods to the spreading nature of Sweet Fern’s rhizomatous nature.

Identifying and Finding Sweet Fern

Sweet Fern is a deciduous, densely branched rhizomatous nitrogen-fixing shrub in the Myricaceae family, which includes Bayberry (Myrica pensylvanica). I often spot it near Blueberry and Bayberry bushes while hiking around Long Island’s Pine Barren region. It may be found growing up to Nova Scotia, southward to Georgia, westward to Tennessee and back up to Minnesota and Saskatchewan. It prefers well-drained, acidic and sandy or gravely soil with full sun exposure. It is considered a pioneer species, showing up in stripped, disturbed areas (including along hiking trails) and thrives when there is minimal competition from other plants.

If you come upon Sweet Fern during the summer, you can often smell it before you see it! It is one of the few aromatics, aside from Wintergreen, I come across in Long Island’s Pine Barren region which is generally unhospitable for many plants due to the overall acidic and sandy soil.  Once you know this plant it is unmistakable! It may be quickly spotted by its “fern like” leaves throughout the growing season which turn a russet-maroon-red in the fall. Plant ID is much harder in the colder months as it blends in with the Blueberry branches and other deciduous plants it grows near. The USDA Forest Service publication on Sweet Fern is a great source for ID information.

A Stabilizing, Nitrogen Fixing Plant

Sweet Fern is one of those fun plants that has a symbiotic relationship with special bacteria that enables “nitrogen fixing”. The bacteria, Frankia bacterium, lives on Sweet Fern’s roots, creating special nodes that help the plant“fix nitrogen” into the soil over time.  This has me wondering about the way this rhizomatous, nitrogen fixing plant is interwoven into the eco-systems such as the Pine Barren region: does the plant assist the soil’s ecology by fixing nitrogen that is otherwise lost and bio-unavailable due to high soil acidity and porosity? This certainly seems to be the case.

According to research by Peter Del Tredici, Sweet Fern plays a revitalizing role for land that has been stripped of plant cover such as through fire, erosion and human intervention such as clear cutting. Sweet Fern, in a sense, is a plant that thrives in harsh conditions and helps improve soil conditions paving the way for other plants to come in that will eventually kill Sweet Fern. A sweet plant, indeed! I look at it and hear it asking: “How may I be of service? Let me set the table for you before you cook and eat me up!”

On that food note, Comptonia peregrina is monoecious, meaning each plant both male and female reproductive organs. Male flowers are catkin-like, reminiscent of Balsam Polar or Birch tree catkins and the female flowers, become burrs that contain several “nuts,” which birds like the Yellow Shafted Flicker like to eat, according to Del Tredici. Truth be told, I’ve yet to nibble on the nuts for the experience and look forward to trying a few.

Harvesting Sweet Fern

Sweet Fern has a long harvest time, especially if looking to harvest the aromatic leaves to make tea or medicine such as a tincture or distill it for the aromatic hydrosol as I do. Harvest the leaves from June up into September, though I prefer to harvest in late June into early July as it seems to produce the most volatile oils when leaves are younger and the sun is near its apex.

Overall Therapeutics of Sweet Fern Leaf

After consulting with herbal books such as Matthew Wood’s “The Earthwise Herbal Vol II: A Complete Guide to New World Medicinal Plants” and working with the plant myself, the consensus is that Sweet Fern (leaf) is warming and astringent. According to Wood, it mildly stimulates assimilation with an affinity for the lymphatic system. In this sense, I often feel a clearing in my head (thoughts) and jaw and neck (lymph) when drinking diluted hydrosol.  Of note, it has also been called Spleenwort given its affinity with the lymphatic system.

Historically, the leaves are used to make a pleasure tea and often substituted for Camilla sinensis leaves. It was, and still is, used in beer making as a supplement or substitute for hops (Forrest). According to an article on Early American Beer making, Sweet Fern was included in a recipe along with horseradish and other herbs to make a “good and healthy diet drink.” (Harbster). Given its sweetly aromatic nature, it is no surprise how, according to Moerman, this plant was used as an incense given its sweetly aromatic nature.  

Sweet Fern, applied topically as a poultice or tea, was and still is used for treating poison ivy rash and general aches and inflammation (Wood and Moerman). In this sense, I would turn to various leaf preparations of Sweet Fern (e.g., poultice, salve, hydrosol, tincture, diluted essential oil) as a go-to for matters of topical irritation such as ivy rash, bee stings, and minor scrapes and swellings.

Notable Chemical Components of Sweet Fern Leaf Essential Oil

Thanks to the increased interested in Cannabis and CBD from the hemp plant (Cannabis sativa) there is more interest and research around “terpene” benefits. Terpenes are the building blocks of aromatic essential oils and of course, found in the aromatic Cannabis sativa plant. Many of the terpene components found in Hemp may also be found in other aromatic essential oils such as my beloved Sweet Fern. One GC/MS (Gas chromatography, Mass Spectrometry) analysis showed how Sweet Fern’s essential oil contains at least 70 chemical constituents where highest percentages are the sesquiterpenes beta-caryophyllene (known for its anti-inflammatory & analgesic qualities), alpha-humulene (aka: alpha-caryophyllene) and the monoterpene, beta-myrcene (both known for their anti-inflammatory, sedative, relaxant qualities) along with Nerolidol (known for its sedative properties). 

Aromatherapy (Essential Oil) properties: Therapeutics of Inhalation

Olfactory aromatherapy (such as diffusion and smelling 1 to 2 drops of essential oil from a cotton pad) offers several benefits to the nervous system. My experience with Sweet Fern essential oil is that its overall personality has an initial stimulating, clearing quality on the mind. The stimulation brings warmth through a subtle increase in circulation. It is an overall circulating, warming stimulant (flow) that eventually calms and nearly sedates and “draws you down.” In my words, the drawing down spreads through the body like Sweet Fern’s rhizomes spread through the soil, not deep but at the surface, the periphery. Smelling the oil and ingesting tea made from the leaves brings similar effect: a slowing down of the mind, almost a bit dulling to the mind and senses. The profile is such that it moves the body (stimulating) but clears and quiets the mind (lulls, nearly stupefies…more work is to be done!).

Sweet fern Distillation with Amy Anthony.

Aromatherapy Blending Ideas with Sweet Fern Essential Oil

Essential oils are highly concentrated substances that must be diluted before using on the skin (with exception, but that is for another class or post), this includes the bathtub, sprays, lotions, salves and body oils. Following are two Aromatherapy applications that incorporate Sweet Fern essential oil to reap the benefits of its calming, soothing and clearing qualities.

Plants of North America: Mist for Clearing and Calming Space and Mind

Materials Needed:

  • 2-ounce glass bottle with fine mist spray top
  • 2.0 fluid oz of distilled water (Optional: Sweet Fern hydrosol)
  • 6 drops Sweet Fern essential oil (Comptonia peregrina)
  • 8 drops Goldenrod essential oil (Solidago canadensis)
  • 12 drops Hemlock Spruce essential oil (Tsuga canadensis)

Usage suggestions: Add the essential oils to a 2-ounce glass bottle with spritzer top and swirl them around to incorporate. Fill the bottle with distilled water up to its “shoulders.” Liberally spray the air in front of you and walk through the mist, or spray your face 2 – 3 times and enjoy the aromatic experience. Always shake the bottle before using and keep your eyes closed! Use 2-3x per day and when-ever you need a pick-me-up.

Topical Oil for General Inflammation, Aches and Pains:

Materials Needed:

  • 1-ounce bottle with flip or pump top
  • 1 fluid oz of Arnica montana infused oil (or substitute Sesame oil)
  • 8 drops Sweet Fern essential oil (Comptonia peregrina)
  • 8 drops Copaiba essential oil (Copaifera officinalis)
  • 4 drops Spike Lavender essential oil (Lavandula spicata)

Usage suggestions: Add the essential oils to a 1-ounce bottle with flip or pump top, swirl the oils to mix them together. Fill the bottle up to its “shoulders” with Arnica oil. Massage the oil into areas of concern as needed.

In closing, I hope you enjoyed this time with Sweet Fern and me (in my garage!). There is still much for me to learn about Sweet fern’s amazing qualities. I am already looking forward to June when I can brush my hands along its leaves and revel in its initially stimulating yet calmingly-nearly-stupefying qualities.

Resources and Citations:


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