Lady Fern forms dense leafy somewhat circular clumps from a shallow creeping rhizome. The showy fronds are 2-pinnate pinnatifid or can be 2-pinnate; the lacyness of the pinnae mark this fern's appearance as the essence of "fernyness."
Fronds: Fronds grow 1 to 3 feet high. They are lanceolate in shape, broadest at or just below the middle and have pointed tips; sterile and fertile fronds look the same topside. The central rachis is smooth or with a few glandular hair. The stipe is smooth, greenish to reddish in color with scattered brown scales. Reddish coloration of the stems occurs sporadically within this genus and is no longer considered a separate variety of the genus. The reddish color seems to last until the fronds are fully developed.
Pinnae: Each blade can have up to 30 to 40 pairs of pinnae (but usually fewer), which are narrow, pointed at the tip and if a stalk is present it is very short. They are arranged alternately on the rachis but closely spaced.
Pinnules: Pinnules are variable in shape, with pointed or rounded tips, veins running to the margins, with the edges formed into deep lobes with toothed margins. When 2-pinnate pinnatifid, the pinnatifid pinnules will be at the tips of the upper pinnae.
Fertility: The sori are of various shapes, generally straight, but not round. Some can be horseshoe shape, some elongated and they can have fine hair. The indusia are attached lengthwise on one side only and have an irregularly toothed edge which the sori, at maturity, appear to push backward.
Fiddleheads: Fiddleheads arise early in the spring and have tan-brown scales which remain on the stipe during the season. Coloration can be green to reddish.
Habitat: Lady Fern grows best in rich, moist, neutral to acidic soil in partial to full shade. Plants in full sun will not do well unless the soil is constantly wet. Clumps can be readily divided in spring or fall. Tattered fronds can be cut off and new ones will grow. There are a number of cultivars available from the nursery trade.
Names: The derivation of the genus Athyrium is obscure. Stern (Ref. #37A) believes it may come from the Greek athuros, meaning 'spiritless'. However, Cobb (Ref. #3a) states that the name is derived from two Greek words: a meaning 'without' and thyrus meaning 'door', the combination referring to the mature sporangia, which barely push back the edge of the indusium, thus appearing as if 'a door did not open'. The species name filix-femina means "lady fern." The genus Athyrium contains only the Lady Ferns which are found in many parts of the world and number around 180 but only two are in North America. A. filix-femina has been divided into 5 varieties, of which 4 occur in North America. The authorship for the plant classification is complex - see notes below the photos.
Varieties: When the blade is 1 to 1.5 times the length of the stipe two varieties are possible. A. filix-femina var. angustum, the Northern Lady Fern, has frond blades that are broadest just below the middle, with narrow bases. Mature spores are golden yellow. A. filix-femina var. asplenioides, the Southern Lady Fern, has frond blades broadest just above the base of the frond and mature spores are dark brown.
When the blade is 2x the length of the stipe two other varieties are possible. Var. cyclosorum where the pinnules are narrowly deltate and almost equilateral at the base, spores yellow; or var. californicum where the pinnules are linnear-oblong, inequalateral at the base, spores brown.
Comparison: The Silvery False Spleenwort, Deparia acrostichoides, is somewhat close in appearance and also has pinnae alternate on the rachis, sori in a herringbone pattern and with the lowest pinnae usually pointing downward, but the pinnules have a rounded to blunt tip and the margins lack the sharper lobes. Also the indusia does not have a toothed edge. That species also has many silvery hairs.
Above: The new fronds of Lady Fern in early spring. This example without the reddish coloration. The fiddleheads emerge with the brown scales that will remain on the stipe during the season.
Below: 1st photo - Emerging fiddleheads with reddish coloration. 2nd photo - newly developing sporophytes just emerged.
Below: 1st photo - The frond pattern seen here is 2-pinnate with each pinna subdivided into individual pinnules 2nd photo - Each pinnule is lobed, with toothed margins and veins running to the margin. 3rd photo - In June, the sori are forming on the underside of the pinnules, in straight, elongated or horseshoe shapes.
Below: Progression of spore release. 1st photo - The indusia, attached to only one side, are being pushed back (note the toothed margin of the indusia). 2nd photo - The sporangia of the sori are visible as spores are released. 3rd photo - The remains of the sori on the pinnule after the sporangia have released the spores.
Below: 1st photo - Example of the various shapes of the sori. 2nd photo - The stipe, showing scales and a greenish-red color.
Below: Newly expanding fronds maintain a reddish coloration until the frond more fully unfolds.
Notes: Lady Fern is indigenous to the Garden, Eloise Butler catalogued it on May 25, 1907. Martha Crone noted planting 209 of them in 1956 when she was developing the Fern Glen. Ken Avery added another 25 to the Fern Glen in 1960. Curator Susan Wilkins most recently planted it in 2006 and 2013. It's range in North America extends from Saskatchewan and the Dakotas eastward to the coast, south as far as Missouri, TN and NC. In Minnesota the ssp. angustum is the species recognized by the DNR and the U of M as the native species. As such it is found in most counties of the state, the exceptions being in the drier SW. The species name of felix-femina that you sometimes find, is not recognized according to them, but is a misspelling.
Plant classification authorship: The first to classify this plant was Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy (the '(L.)' in the authorship). He originally assigned the name Polypodium filix-femina in 1753. Two others added to his work. First is ‘Roth’ which refers to Albrecht Wilhelm Roth (1757-1834) German botanist who published his research and was later associated with the University of Jena Botanical Institute. His published work was improved upon in 1799 by ‘Mert.” who is Franze Carl Mertens (1764-1831), German botanist, a friend of Albrecht Roth. He published the 3rd edition of Deutschlands Flora. The genus Mertensia is named for him.
The variety angustum, was described by ‘Willd.’ in 1810 who put it into the Aspidium genus - this was Carl Ludwig Willdenow (1765-1812), German botanist, a founder of the study of the geographic distribution of plants. He was director and curator of the Botanic Garden of Berlin. His work was then amended in 1864 and placed in the current genus by ‘G.Lawson’ who is George Lawson (1827-1895) Scottish-Canadian botanist, considered the Father of Canadian botany. He helped create Canada’s first botanical garden.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"