(Editor's Note: This article was originally published on November 8, 2008.)
Pteridomania was a phenomenon of the Victoria Age, between the mid- and late-1800s. Pteridomania was not a rampant disease, rather an obsession with anything related to ferns! The Victorians were mad about ferns, whether growing them or illustrating them as decoration on various objects. Fern enthusiasts would travel all over the British Isles looking for unique ferns. Foremost among the ferns they sought was the lady fern, Athyrium filix-femina. Every subtle difference in frond structure would constitute a new cultivar. By the end of the 1800s some 300 different selections were described! Alas, most of these are lost today but a handful still exist to this day.
There are about 100 species of Athyrium worldwide. They range from the tropics to the Arctic Circle. Most are clump-forming plants. By far, the most important species is the lady fern, A. filix-femina. When you consider that this is the hardiest (USDA Zone 2) and only Athyrium species found across the whole northern hemisphere, then its popularity is understandable. Culture is easy: any reasonably organic, moist soil will do. The wetter the soil, the more sun they can handle. Acidic soil is best but they will tolerate alkaline soil. While historically there were hundreds of described cultivars, today there are about thirty you may encounter. Many are only subtly different and fall into certain ‘groups'. I will stick to describing just a few.
The wild species itself is quite attractive with lacy, light green fronds reaching one meter in length. The Cristatum Group is composed of many cultivars, all which have the tips and/or edges of the fronds ending in small, flat, fan-like crests. Some of the cristatum-like selections have their frond tips bunched with many crests, lending the appearance of parsley. These are called the Corymbiferum Group if the parsley-like tip is narrower than the rest of the frond, or the Grandiceps Group if the fluffy tips are wider than the remaining frond. The Plumosum Group has fronds so finely divided that they appear distinctly feathery--very attractive!
The wild species of A. felix-femina and one of the crested forms, 'Vernoniae-Cristata'
‘Victoriae' has long, narrow fronds whose pinnae are narrow and arranged in an X-pattern along the stipe. The pinnae tips are also crested, adding to the unique form of this selection that dates back to 1861. ‘Fieldiae' is an even more extreme form that is longer and narrower than ‘Victoriae'. ‘Dre's Dagger' is a modern-day, smaller version of ‘Fieldiae'. All of the fern selection with this cross-like arrangement of pinnae are classified as being members of the Cruciatum Group. ‘Frizelliae' goes to the other extreme being dwarf (10 to 20 cm) with narrow fronds and small rounded pinnae. This one looks more like a spleenwort fern, Asplenium trichomanes. Also extreme is ‘Acrocladon' and ‘Unco-glomeratum' whose fronds are short and multiple-branched, lending the entire plant a tufted, very parsley-like look.
The unusual cultivars 'Victoriae' and 'Frizelliae'
There are three other native North American Athyrium species you may encounter. Athyrium alpestre (A. distentifolium), the alpine lady fern, is not unlike a smaller version of the common lady fern. Despite the name, this fern is not as hardy (Zone 4) as A. felix-femina. The other two species, A. pycnocarpon (narrow-leaved glade fern) and A. thelypteroidesT (silvery glade fern) produce a running rhizome from which arise individual narrow fronds. Superficially they look like New York fern (Thelypteris noveboracensis). Both are rated for Zone 5 and reach 45 cm and 70 cm respectively. These latter two species will tolerate dry shade but will appear more lush if the soil is reasonably moist.
The alpine lady fern is often found tucked among rocky crags
Most of the other garden-worthy Athyrium hail from Japan and China. Of these, the most important is the Japanese Painted Fern, A. niponicum ‘Pictum'. This fern has enjoyed a surging popularity for two reasons. First, it is among the hardiest of the east Asian species (Zone 4) and secondly, it is one of the few ferns that are available in a colour other than green! Athyrium niponicum ‘Pictum' is perhaps one of the most sought after ferns for all gardeners, not just fern enthusiasts. Certainly, this selection was partly responsible for introducing modern gardeners to the attributes of ferns as a garden ornamental. ‘Pictum' has wine-purple stipes contrasting with fronds that are silvery-grey blended with green. When first introduced to North American gardeners, plants fetched a high price; but today they are as inexpensive as the more common landscape ferns.
Athyrium niponicum 'Pictum' along with some spinoffs which include 'Applecourt', 'Burgundy Lace' (top row) 'Silver Falls' and 'Ursula's Red' (lower row)
This fern is quite compact compared to many, with plants forming tufted clumps with fronds to 35 cm. Due to its size and unique colour, it is best placed near the front of the shady border. This one is even small enough to use in shady rockeries and lends itself beautifully to containers. In recent years there have been a rash of new cultivars derived from ‘Pictum'. These all have varying shades of silvery-grey fronds blended with touches of red. Cultivars include ‘Applecourt', ‘Burgundy Lace', ‘Pewter Lace', ‘Red Beauty', ‘Regal Red', ‘Silver Falls' and ‘Ursula's Red'. Even more recent are a pair of hybrids between ‘Pictum' and the common lady fern. These are ‘Branford Beauty' and ‘Ghost'. Both have the silvery fronds of ‘Pictum' but are larger in size due to the A. felix-femina influence.
The hybrid painted ferns 'Bradford Beauty' and 'Ghost'
Another popular Japanese Athyrium species is A. otophorum. This compact fern will reach to about 50 cm and has new fronds that are distinctly reddish. As they mature, the fronds turn green but the stipes remain wine-red. This species, which is rated for Zone 6, remains green longer into the fall season than any other Athyrium species. Another east Asian species of note is A. vidalii (zone 6) whose compact 35 cm fronds arise reddish like A. otophorum but mature to grey-green. Athyrium palustre (Zone 7) appears much like a taller, more erect version of A. niponicum ‘Pictum'.
Two other Asian species are A. otophorum and A. vidalii
If you are a fern enthusiast, you no doubt have a least a couple of Athyrium in your collection. If you simply are looking for an interesting foliage plant for a shady site, then the Athyrium ferns come highly recommended.
I would like to thank the following people for the use of their photos: growin - 'Burgundy Lace'; Valentina_S - 'Ursula's Red'; gregr18 - 'Applecourt' and 'Victoriae'; mygypsyrose - 'Silver Falls'; gretaduck - 'Vernoniae-Cristata'; Snowrose - 'Ghost' and weebles64 - 'Frizelliae'