Wild Seed Project Native Plant Profiles: Christmas fern. Polystichum acrostichoides. Dryopteridaceae
Wild Seed Project: Returning native plants to the Maine landscape
December 2015

Evergreen fern of moist forests; grows in neat clusters of two or three plants, or in small colonies; prefers light to full shade, but will tolerate sun if soil is humus- rich and moist; ranges from Nova Scotia and Ontario, south to Florida and Texas.

By Pamela Johnson

Ferns were a puzzlement in early botany. Most familiar, seed-bearing plants gloried in sunlight and manifested their life cycles in the warmth of spring and summer. The ferns were anomalous in form and location, therefore, mysterious. The absence of flowers or seeds, their morphologies, and the ferns’ preferences for cool shade promoted superstitions, unease, even fear, in the Middle Ages. At a time when “witchcraft [was] heresy and not believing in it [was] also heresy”, according the Malleus Maleficarum (1486), ferns were familiars of witches and “the gossip of old crones”.[1]

Ferns belonged to the nightmarish and impious territory of untamed land and dark forests, where fear eclipsed facts. Also, a plant without visible seeds could not be replicated and cultivated for food, medicine, profit or pleasure. Seed collection and plant husbandry were a kind of dominion in a frightening, perilous world.

Folklore and a few early chronicles reported that ferns did flower, but in secret, and perhaps only once a year. Some medieval herbalists, who were the first “botanists”, thought ferns could be spied upon and caught in furtive bloom. Hieronymus Bock wrote, in 1539, in his New Kreüter Buch:

I have foure yeres together one after an other upon the vigil of saynt John the Baptiste (which we call in English mydsomer even) soughte for this sede of Brakes upon the nyghte, and in dede I founde it earlye in the mornynge before the daye brake, the sede was small blacke and lyke unto poppye. I gatherid it after this maner; I laide shetes and mollen leaves underneth the brakes which receyved the sede . . . I went aboute this busynes, all figures conivrynges, saunters, charmes, wytchcrafte, and sorseryes sett a syde, takynge wyth me two or three honest men to bere me companye.[2]

Suspicions of ferns eventually withered. The wild claims of the Doctrine of Signature (De Signatura Rerum, 1622), which guided European herbalists into the early 18th century, removed some of the malevolent connotations of ferns. The divine signature of maidenhair fern (Adiantum species), for example, was derived from the snarled, hairlike roots and wiry stems of the fern, “indicating” a cure for baldness. Bracken fern (Pteridium aquilinum), a cosmopolitan species, was eaten[3], fed to some livestock, harvested and dried for human and animal bedding and roofing. In other accounts, including Shakespeare’s only reference to ferns, the illusive fern “seeds” were thought to confer invisibility. And in the greatest reversal of symbolism, dried ferns were carried for protection. They became emblems of sincerity, perhaps because they were just so green.

Fern reproduction remained a mystery for many centuries. Hieronymus Bock (1498-1554) advanced the general study of plants in New Kreüter Buch (1529). A pioneer of descriptive botany, phytography, he was the first to investigate the life histories of plants beyond their flowerings and anthropogenic uses. He also sought a classification system that anticipated Linnaeus. However it was not until 1851, when the Leipzig botanist Wilhelm Hofmeister (1824-1877) identified ferns’ spores, that the plants were truly lifted from the murk of primitive understanding and misapprehension. Hofmeister’s explanation of alternating generations, the ferns’ reproductive cycle, was a botanical milestone.

The ferns we encounter in Maine have an ancient lineage. Ferns were the first vascular plants, appearing (in the Devonian period), millennia before there were flowering plants, grasses, shrubs or trees. Though the earliest ferns did not survive the aeons, their mass, with other early plants, provided the basis for the Earth’s coal deposits. Included in fern antecedents were the unsuccessful “seed ferns”.

There is still a whiff of the antediluvian, wading through waist-high swales of fiddlehead ferns (Matteuccia struthiopteris) in aqueous light- a kind of whiplash to the Carboniferous when ferns were tree-sized dominants, and dragonflies in the vaporous air would have had wingspans of six feet or more.

Modern ferns, which comprise between 12,000 to 15,000 species worldwide, are generally, with the exception of a few tropical species, smaller versions of the prehistoric arboreal ferns that once reigned. Flowering plants are now predominant, while ferns mostly occupy the herbaceous layer of understory.

The landscaping value of ferns is underutilized by many gardeners, seduced as we all are by colorful flowers and the inexorable novelties thrust upon us by the nursery industry. Take a walk in the woods in winter, however, and you might learn quite a bit about ferns, without the usual, high-season distractions.

Christmas fern, Polystichum acrostichoides, is one of our most recognizable ferns. Its sturdy greenness in upright clumps is unmistakeable. Christmas fern is truly, eloquently evergreen, and its fronds were popular colonial American and Victorian seasonal decorations. There is a festive resilience about this fern, so very wholesome in winter’s reductions.

H.D. Thoreau asks: “What means this persistent vitality? Why are these spared when the brakes and osmunds were stricken down? They stay as if to keep up the spirits . . . in them I feel and argument for immortality. Death is so far from being universal . . . How valuable they are for cheerfulness. Greenness at the end of the year, after the fall of the leaf, a hale of old age . . . ”

Henry David Thoreau, “The Dispersal of Seeds”

Christmas fern grows in tidy, medium-sized clusters. Its shiny fronds darken with age, and the fertile, spore-bearing tips of the fronds may break off late in the year, but overall the fern has a staunchness that makes it easy to identify, as well as admirable. The Christmas fern has a bouquet-like appearance, as if the rootstock were an underground fist offering a tribute of greenery from the forest floor.

Sometimes called holly fern for the dentation along its leaflet margins, it is also called Christmas-stocking fern because each leaflet has an odd, upward-facing projection at its base.

When winter has done its worst, last season’s Christmas fern fronds finally succumb to gravity and fan onto the ground. From the center of the plant arise silvery, white-scaled croziers of new growth. Croziers are the circinate heads of young fern fronds, and are also called fiddleheads.

Acquaintance with ferns requires some adjustment to fern-specific botanical terminology- not a necessity, but helpful for identification. “Frond” refers to the entire fern leaf including the “stipe”, the stalk, which emerges from a rootstock or rhizome and connects the root to the “blade”. The blade is the expanded leafy part of the frond, whose stem part is called the “rachis” or axis.

A fern’s blade may be simple and undivided or compound, divided into leaflets like the Christmas fern’s. These leaflets are called “pinnae” (pinna is Latin for feather, wing or fin, pinnae is the plural form). A divided blade is a pinnate blade, or once-cut blade. A twice-cut blade has “pinnules”, or sub-leaflets; a thrice-cut fern blade is tripinnate with “pinnulates”. The mid-rib of a pinnule is called a “costa”.

Leaflet morphology provides sufficient information to distinguish many fern families. But sometimes identification depends upon examination of the spore-producing parts of ferns. A few ferns have entirely separate fertile structures: most familiar may be the beaded stalks of the sensitive fern (Onoclea sensibilis). Most ferns produce spores on the undersides of their leaves or leaflets; the size, shape, and arrangement of the spore cases, “sporangia”, are peculiar to each fern.

For those who still like to read and carry field guides, Boughton Cobb’s Ferns is exemplary. First published in 1956, the tenth in Peterson’s Field Guide Series, the book is illustrated with precise line drawings by Laura Louise Foster, and contains exhaustive diagnostic detail. Some ferns have lately been re-shuffled into different genera and families, and Cobb’s nomenclature may be out-of-date. The guide’s utility, however, is timeless.

The New England Wildflower Society proclaimed 2002 “The Year of the Ferns” and devoted its Conservation Notes issue to the celebration of ferns. In an interview with Patrick Chassé (and three other New England-based landscape designers), there is a valuable approach to using ferns in garden designs. Chassé talks about the “‘non-emotional’ and ‘emotional’” deployment of ferns. The former is utilitarian, planting ferns, perhaps, in tough sites, for coverage for deer-proof solutions. The latter use “create[s] a sense of refuge [where] ferns suggest a mature forest, providing ‘the feeling of an undisturbed, quiet, and established place’.”[4]

This is helpful advice, along with the admonition that ferns appear to best advantage when given the best light and soil conditions they prefer. Christmas fern is not a garden fuss-pot, but it will thrive in richer, well-drained soil, sheltered from blazing sunlight; that is, in conditions similar to where it lives in the woods.

Frances Theodora Parsons (Mrs. William Starr Dana, author of How to Know the Wildflowers) wrote How to Know the Ferns in 1899. In her introduction she says:

“. . . one of the great advantages of ferns . . . lies in the fact that the number of our native, that is, of our northeastern, ferns is so comparatively small as to make it an easy matter to learn to know by name and to see in their homes perhaps two-thirds of them.”

She continues, “the greatest charm the ferns possess is that of their surroundings. No other plants know so well how to choose their haunts.”[5] Winter is a fine time to begin to know the ferns. Search for the evergreens of Christmas fern or the lithophilic rock polypody (Polypodium virginianum) which marches in battalions across the tops of glacial erratics. Look for the rusty, supine mats of eastern hay-scented ferns who still blanket swaths of the forest floor though their leaflets are skeletized. And notice how fern rootstocks nestle happily among large tree roots, or how the leafless stalks of some ferns look like tawny clumps of coarse grass. Study the ruined leaflets and sporangia that frost emphasizes on a dry, cold morning. Learn what you can in this spare season.

 

In nature, ferns often germinate in moss, in a rotting log, or in damp exposed soil in shady locations, such as by a stream. Fern spores can be propagated indoors on a bright windowsill, out of direct sunlight, or under a grow light. See the fern propagation section on the website for detailed instructions. Some ferns can be propagated by dividing the roots in the fall or very early in the spring, well before the new fronds are ready to unfurl. In Maine, many nurseries still sell ferns dug from the wild. This is often damaging to wild populations and makes it difficult for nurseries who propagate plants to compete. When purchasing ferns, ask that they are nursery propagated.


[1] Blunt, Wilfred and Sandra Raphael. 1979. The Illustrated Herbal. New York: Thames and Hudson, Inc. p.132.

[2] Ibid, p.132.
[3] It must be noted that ethnobotanical references to bracken fern stress the toxicity of the plants at various stages of growth. Arthur Haines in Ancestral Plants, Vol 1. writes: “Pteridium aquilinum is believed to be carcinogenic, and regular and prolonged consumption is suggested to lead to various types of cancers . . . ”. Haines, Arthur. 2010, Ancestral Plants, Vol. 1 Anskimin
[4] Smarr, Tom. 2002. New England Wildflower: “Landscaping with Ferns”;NEWFS: Framingham, MA. p.25
[5] Parsons, Frances Theodora. 1966. How to Know the Ferns. New York: Dover Publications, Inc.;pp 10-13.