The maidenhairs are popular and beautifully irresistible, delicate-appearing plants that evoke the traditional image of fern in the mind's eye of the gardening public. "The maidenhair fern . . . is one of the few species with which those who make no pretense to botanical knowledge are usually acquainted" (Clute 1901). There are some 150 to 200 species scattered over the world's various fern habitats with a rich assortment of natives populating favored sites in the American tropics.
Given their widespread distribution and range of habitats, there is truly a maidenhair ready to adapt to a garden or household niche. Old favorites and exciting new imports offer gardeners in temperate zones increasingly broad options for light and refreshing additions under the woodland canopy. And for indoor décor or outdoor enrichment in frost-free gardens, there's an even wider selection of varied and exotic decorative material.
The genus Adiantum is easily recognized by its fronds with glossy, brittle stipes in shades of black, blue, and chestnut, and tissue-thin wedge to rectangular sculptures of green pinnae. Fan-shaped, horizontal blades are familiar hallmarks, but variations on triangular foliage, while less recognized as a signature trademark, are common for both outdoor and greenhouse or houseplant choices. The veins are free and forking and there are one or two vascular bundles. Spores are produced marginally in sori protected under an inrolled false in-dusium. Unlike the sori of closely related genera, Adiantum sori are attached to the indusial segments rather than to the pinnule.
Most maidenhairs are easily propagated. Those that scamper about on creeping rhizomes can be divided in spring or fall with spring being the option of choice in the midwestern and eastern United States, and either season being appropriate for western gardeners. Most are easily grown from spores,
A cultivar of Adiantum raddianum with Pyrrosia lingua in the Fernery at the Morris Arboretum.
Sori of (left to right) Adiantum chilense, A. capillus-veneris, A. venustum, and A. monochlamys.
which, in the Pacific Northwest at least, mature very late in the season, usually September. The exception, unfortunately, is the beautiful and highly in-demand Adiantum venustum. In spite of many experiments and studious trials involving variations in timing, soils, and light by many seriously dedicated propagators, it defiantly resists spore culture. Some theorize that because the species can spread and maintain itself by creeping rhizomes, there has been little adaptive advantage to creating new generations from spores. This supposition applies to numerous species (besides the Adiantum of our attention, but including the bracken fern) with extensive and expanding rhizomes. Meanwhile, in the long term for a given number of species, such as our subject, A. venustum, lack of viability could easily be a genetic dead end. No need for horticultural gloom, however, as tissue culture is providing material for eager growers to distribute.
Adiantum comes from the Greek adiantos, which means "to shed water" or "unwettable" and refers to the inferred water-repellent characteristic of maidenhair foliage. (There are exceptions, of course, but the Greeks of a.d. 100 or so should not be held responsible for the undiscovered maidenhair cousins in as-yet-unexplored habitats.) The common name has a more fanciful collection of legends ranging from the mundane (the resemblance of the stipes and roots to lady's tresses) to a folkloric account of a German maiden whose lover turned into a wolf. In flight she tumbled over a precipice catching her black hair in the bushes where the hair took root and sprouted into our familiar fern. Today the "maiden's hair" surrounds a spring, called the Wolf's Spring, at the spot where she landed.
Historically the genus contributes to a plethora of purported herbal cures, potions that offered protection from less-than-kind magical spells, and assorted practical uses. To this day Native Americans use dark black-mahogany accents of locally available maidenhair stipes to create contrasting elements to the tan reeds in their beautiful basketry. In earlier times the highly alkaline fern ashes were used in making lye and, in combination with oil and fat, soap and shampoo. The concoction was also a treatment for skin diseases (and dandruff?). Traditional herbal recommendations are varied and
imaginative with a range of treatments for ailments that include asthma, "stones," and snakebites. The most famous maidenhair "cure," however, is the mother of all cough medicines, the Syrup of Capillaire from France. The recipe:
Maidenhair leaves 5 oz. [142 g] Licorice root, peeled 2 oz. [57 g] Boiling water 5 pints [2.5 l] Let stand six hours and then add Loaf sugar 13 lbs. [6 kg] Orange water 1 pint [0.5 l]
(And stir!) I do not know what this did for a sore throat, but the sugar high must have been absolutely amazing. (By the way, do not try this at home.) In time, it was decided that the maidenhair foliage was superfluous so the syrup became licorice/orange-flavored sugar, with various alcohol related additives replacing the attributes of the fern. Anything for a sore throat.
Today the maidenhairs are prized for their decorative properties indoors or out. In the temperate garden they add a cheerful lightness-of-being complement in filtered shade and moist compost. Their airy grace gives a buoyant visual relief to the somber elegance of broadleaved evergreens, those structural midlevel garden elements that offer a flowing continuity
Adiantum raddianum 'Gracillimum' with begonia leaves. Photo by George Schenk.
Feathery froth of Adiantum venustum in the spring.
of design from the overstory of deciduous trees or the even larger coniferous patriarchs of garden shade to the woodland floor. Give them the company of wildflowers, fellow ferns, and carefully selected ground covers, and space to display their welcome wands of soft sylvan charm.
Those maidenhairs that add elegance outdoors are beloved by gardeners, but houseplant enthusiasts often bemoan the performance of indoor offerings. With their ephemeral and delicate structure, the plants entice and seduce from the shelves of the grocery store to favorite garden centers and all too often collapse as soon as they arrive in the home environment. Their airy appeal does indeed require customized care, and the more humidity the better.
Grouping like-minded plants so that they share their evaporation with each other helps to provide the required humidity. Another popular option is to stand the pot(s) on, but not in, a tray with pebbles and water so that the constant source of wispy vapors keeps the plant(s) appropriately comforted in a pseudo-greenhouse environment. It is tempting as well as disastrous to mist the foliage. The droplets can linger on and rot the leaves. (This applies to many other indoor ferns especially those with congested foliage. The dense fronds of assorted nephrolepis are particularly vulnerable.)
Give indoor maidenhairs good light, but not direct sunshine. The lightly shaded window is ideal, but mind you not too close to hot or cold glass panes. Brightly lit bathrooms where steam from showers regularly boosts humidity levels are select sites. Like most plants, however, even shade lovers, maidenhair ferns tend to direct their new growth towards light, so give pots a 90° turn periodically. Finally they should be protected from the drafts released by doors open to outdoor cold or, by contrast, the dehydrating breezes of forced air heat.
Plant your collections, indoors or out, in a healthy potting mix consisting of light composty soil and enough of a gritty additive to ensure good drainage. Containerized maidenhairs do not like to be overpotted, so choose a container just larger than the root ball. When it is time to transplant, move to the next larger sized pot with no more than 1 in. (2.5 cm) of fresh soil around the perimeter.
Feeding of plants in pots is not optional as nutrition is rapidly consumed. There are several choices, with the most popular recommendation being a light meal of a very strongly diluted, evenly balanced (10-10-10, 14-14-14, 20-20-20) fertilizer applied regularly throughout the growing season. Other growers use the same evenly balanced formula, at one-half strength and sparingly, with the arrival of new growth, once a year and let that application supply nourishment throughout the season. Both methods work. However, with either option let the fern rest when it is not producing new foliage. Caution! Do not use a slow-release fertilizer on indoor ferns. And be warned: if you have cats or kittens, stay away from fish-based formulas which will invite the "curiosity of the cat."
More indoor ferns are killed by kindness in the form of overwatering than any other complication. Maidenhairs lead the list. Stagnant water at the roots sours the soil and the plant. Wait until the surface of the soil is dry or the pot feels espe cially light when lifted. (However, do not wait until the fronds wilt. Though adiantums will recover and produce new fronds, they will not rehydrate.) Then give the pot a good soak with warm water. Maidenhairs do not like a cold shower any more than I do, and furthermore it takes a full day for the soil to reheat and revert to its preferred room temperature. I am frequently asked, "Well how often?" This of course depends on the soil, room temperature, and exposure and must be individually determined. For a controlled supply of moisture, an excellent option is to double pot. Place your prize in a clay pot and sink that pot into a slightly larger container surrounded by a 1-in. (2.5-cm) buffer of sand or sandy soil that can be watered as necessary. The clay pot will wick the water and keep the maidenhair happy with an even supply of moisture. (This system works well with the whole spectrum of indoor ferns and friends.)
For grooming, which if neglected turns into quite a chore, give the plants a complete haircut just as the new fronds are emerging. In northern climates this is normally as daylight increases in springtime. In Southern California and Florida, it can be almost any time. A missed opportunity means removing fronds one by one, which can keep you out of trouble for quite awhile.
All said, your garden maidenhair population should provide years of decoration, and it is possible (truly) to keep your indoor maidenhairs in good health even away from their preferred greenhouse conditions. A little experimenting (along with a steady plant supply) helps.
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