EGARDENING                            Last modified December 12, 2006

Gardening with natives links

 


Bulbil and sori on a Bulblet Fern (Cystopteris bulbifera)

Gardening with native ferns
by Catherine Kavassalis

...Fair ferns and flowers, and chiefly that tall fern,
So stately, of the queen Osmunda named;
Plant lovelier, in its own retired abode
On Grasmere's beach, than Naiad by the side
Of Grecian brook, or Lady of the Mere,
Sole-sitting by the shores of old romance...

from  A Narrow Girdle of Rough Stones and Crags, William Wordsworth 

Perhaps romantic poets like Wordsworth helped to hasten in the pteridomania of the Victorian era. For during the mid 1800s, gardeners were decidedly fern crazy, and undoudtedly the royal fern (Osmunda regalis) would have graced many a Victorian Garden. Ferns were widely grown both in outdoor ferneries and indoors in Wardian cases.  These closed glazed cases (essentially terrariums) were invented by a Dr. Nathaniel Ward, in 1829, to transport ferns and other plants around the world.  Ornate versions of Wardian cases became popular for raising ferns and other exotic plants indoors. Fern collection in England became so exuberant that many native species were brought close to extermination. Thankfully, by the late 1860s, the fad had begun to subside and wild fern populations were able to recover.

I begin with this bit of history as a gentle reminder that although I would encourage you to make greater use of native ferns in your gardens,  I also hope that you are respectful of our wild fern populations. That said, there are over two dozen genera of native ferns in Ontario, with many species well suited to home gardens. 

I adore Pteridophytes. These ancient winged keepers of invisible seed hold a special magic for me. The first time I saw the spores of my Christmas fern (Polystichum acrostichoides) shoot across the glass on my microscope stage, I was enwrapped. Beneath each fertile fern frond lies unique sori, clusters of spore cases, which help to identify the various species. In some species, like the Christmas fern, spores are encased in a spring like annulus that literally explodes when conditions are right - a warm microscope light. In nature, the annulus launches tiny spores into the air, where they can be swept high into the atmosphere and around the globe. In the right medium (for instance: equal parts of loam, leaf mold, peat and coarse, well-washed sand) spores will germinate and produce a small heart shaped plantlet (1-3 mm) called a prothallus. When there is sufficient moisture, sperm produced by this little plantlet can fertilize its eggs and a fern, as we know it, is born. You can collect spores in the wild and attempt to germinate them yourself. Some ferns like the Bulblet fern (Cystopteris) produce little bulbs on the back of fertile fronds and these can be pinched off and planted gently in the soil. Other ferns, like the Walking fern (Asplenium rhizophyllum) can be propagated by rooting the leaf tips. These ferns appear to "walk" over forest floors as  fronds arch over and the tips root and form new plants. Such is the magic of ferns.

There are many wonderful native ferns with which to experiment in your garden. I have listed a few here that you might enjoy.

Native Ferns for Home Gardens

for partly to moderately sunny sites

for partly to deeply shaded sites
Athyrium filix-femina 
Lady Fern grows from 60-90cm with finely cut foliage, best in moist acidic soil, but tolerant of other conditions.		 Adiantum pedantum
Maidenhair fern grows from 30-60cm and offers vivid green pinnules on shiny black stems. This decorative beauty tolerates alkaline conditions and grows well in all but the driest of garden sites.
Dennstaedtia punctilobula
Hayscented fern grows from 30-45cm with light green lacy foliage and forms large colonies. Moist, well-drained and acidic soils are preferred although it tolerates most.		 Asplenium rhizophyllum Walking Fern, 30-60cm, loves to creep across moist shady limestone.
Dryopteris filix-mas
Male fern 60-90cm attractive clump forming fern. Easy to grow with elegant robust foliage. Able to withstand a sunnier site and drier soil than most hardy ferns.		 Cryptogramma acrostichoides
Parsley fern or Rock Brake is a small parsley like, practically evergreen fern, 12cm. Tolerant of summer drought. (Cryptos is Greek for hidden and gramma for line - this refers to the lines of sporangia hidden under rolled leaf margins.)
Matteuccia struthiopteris
Ostrich fern forms large, striking clumps of 90-130cm tapering fronds, good for alkaline soils. Easy to grow. Lushest in moist dappled shade but tolerates dry conditions well.		 Cystopteris bulbifera
Bulblet fern is delicate lacey yellow-green fern, 30-45cm, tolerant of dry conditions. Uniquie pea like bulblets form on fertile fronds. Delightful. (I have one growing well in full sun.)
Onoclea sensibilis
Sensitive fern has light green large lobed leaves and is sensitive to frost, 60-90cm. Fertile leaves are balled. This fern favors moist conditions, but can live happily in average soil.		 Dryopteris species
Evergreen species like D. marginalis or D. intermedia
are superb easy to grow 45-60cm ferns for a low maintenance shady borders.
Osmunda claytonia
Tall fern, 90-130cm, with fertile spores interrupting pinnae. It can tolerate dry alkaline soil but needs  moisture in sunny positions.		 Gymnocarpium species
  Oakferns like G. dryopteris, have delicate, triangular fronds held horizontally. These diminutive ferns, 10-20cm, are tolerant of alkaline soils, but often prefer cool moist woodland settings.
Osmunda regalis
Royal fern is a distinctive and spectacular fern reaching 180cm in ideal rich, moist, acidic soil. It grows well in shade, but tolerates full sun if it receives plenty of moisture.		 Osmunda cinnamomea
Cinnamon fern has dramatic architectural form, 90-150cm, prefers moist acidic soils, part sun to deep shade. The fertile fronds arise in spring just above the sterile foliage
Woodwardia virginica
Chain fern has shiny fronds similar to the Cinnamon fern but generally smaller, to 120cm, with a lovely spreading habit, adaptable but prefers wet acidic conditions. Can be invasive.		 Polystichum species
Christmas or holly ferns bear sturdy dark evergreen fronds, 60-90cm,  that are effective in mass plantings evergreen groundcover. They are tolerant of dry conditions.

For a great read on ferns, I highly recommend Robbin Moran's A Natural History of Ferns. Tom Stuart's Hardy Fern Library is the best online fern identification site http://hardyfernlibrary.com/ferns/home.cfm. Visit my web links for more information and references http://www.haltonhelps.org/Egardening/NativeFerns.htm.

May toads nestle in your flower beds and help you tend your beauties in the spring.

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Links and Definitions

 

Some basic information:

Fern = pteridophyte in the division/phylum pterophyta - the second largest division of the plant kingdom (ptera, ptero = wing, feather)

A frond is a mature fern leaf. The shape and degree of leaf division helps to identify the various species in the field.  Some ferns are very simple, like the Walking Fern (Asplenium rhizophyllum) and the fronds are long and simple, unlobed blades. Most ferns have a feathered appearance with distinct leaflets attached to the main blade. These leaflets are called pinnae (singular: pinnules or pinna). If the leafleats are distinct, as in the Common Polypody (Polypodium virginianum) or the Christmas fern (Polystichum acrostichoides), the fern is termed pinnate. If the pinnate lobes are not discrete but connect at the base, as in the Sensitive Fern, (Onoclea sensibilis), the leaf is said to be pinnatifid. Often ferns display more complex form like Marginal Wood Fern (Dryopteris marginalis), which exhibits pinnate-pinnatifid to purely bipinnate character.  Lacy ferns like the Spinulose Shield Fern (Dryopteris carthusiana) have thrice cut blades that can be tripinnate-pinnatifid. 

In addition to the leaf form, the color and character of the stems and ribs can help identify ferns. Most ferns have a stipe or petiole emerging from the rootstock or rhyzome.  This leafless stem becomes the central axis of a fern blade. Where the leaflets form, the stem is termed rachis. In compound, leaves the midribs are called costa.  The petioles, rachis and costa can be smooth and hairless (glabrous) or have hair, scales and glands. Such characteristics can help separate species for field identification.

Perhaps the most useful key in identification is the appearance of the fruiting bodies or sporangia - tiny sacs containing spores. Sporangia are carried on fertile leaves or on  modified leaves. Distinct fertile leaves are found on species like the Cinnamon Fern (Osmunda cinnamomea) or Ostrich fern (Matteuccia struthiopteris). These "flowering ferns" are unique in that the sporangia are borne on nonphotosynthetic leaves - termed dimorphic fronds.  Most species in Ontario do not have dimorphic fronds. Instead, fertile and sterile fronds are similar in appearance and the sporangia are found in clusters, called sori, on the underside of the fertile leaves.  Sori have distinctive shapes, colours and positions. For instance, in Common Polypody (Polypody virginianium) the sori are arranged in discrete rows of round, bright orange/yellow dots between the margin and midrib of each pinnule. In Polypody, Grape Fern (Gymnocarpium) and Beech Fern (Phegopteris), the sori are exposed, but more often, the sori are covered by a thin umbrella-like structure called an indusium.  This is typical in ferns from the families: Aspleniaceae, Blechnaceae,  Dennstaedtiaceae and Dryopteridaceae, which includes the Spleenworts, Chain Ferns, Wood Ferns and Shield Ferns, etc. Upon maturity, the fragile indusia retract or fragment to allow release of the spores. Other ferns protect their spores by folding over leaf margins forming what are termed false indusia. These are present in such species as the Maiden Hair Ferns, the Lip Ferns and Parsley Ferns. (Most members of the Pteridaceae family have false indusia).  Finally, there is the Bracken Fern (Pteridium aquilinum) that has a true indusium underneath a false indusium - double protection. Observation of fruiting bodies along with plant form and location is generally sufficient to place a fern into a particular family and narrow the species possibilities. For confusing species, subspecies and hybrids, a microscope may be necessary for closer examination of vascular structures that permit the transport of water and nutrients and spores.

Knowing what you are looking at is critical, if you are considering harvesting fiddleheads for consumption. A fiddlehead or crosier is a coiled newly emerging frond. The fiddleheads of Ostrich fern (Matteuccia struthiopteris) are considered edible. Although bracken fern (Pteridium aquilinum) fiddleheads are also considered edible and traditionally consumed in Japan, scientists suggest the high incidence of stomach cancer may be associated with the popularity of this carcinogenic vegetable (they contain ptaquiloside). Other ferns are quite toxic.

 

More Information:

Field Identification

Info about ferns

Misc.