Indoor Ferns as Living Fossils
Mention the word "fern" and it conjures up a vision of lovely shades of green, fine, feathery fronds and elegant leaves. Quite apart from this image, this fascinating class of plants, which today numbers some 9,500 different species, holds a number of other surprises for the interested plant lover.
Relics from the carboniferous era
The evolution of fern plants began as far back as 400 million years ago in the earliest periods of Earth’s history, long before the rise of seed-bearing plants. Ferns were at their most abundant during the carboniferous era when gigantic forests of tree-sized ferns and mare’s tail plants covered the planet. They played a major role in the formation of our present-day coalfields. The visible proof of this is the many fossil ferns which are constantly found and which allow a continuing investigation of the vegetation of the carboniferous period. The development of ferns coincides with a very interesting phase of evolution.
During this time, lifeforms that originally lived in the seas were beginning to colonize dry land. Within the plant world this development coincided with the appearance of mosses and ferns. Ferns, therefore, including ancient fossil ferns as well as Lycopodia and mare’s tail species, can truly be said to belong among the most ancient higher terrestrial plants.
Life in the most varied types of climate
Steady temperatures, shade and high humidity, which constitute the typical climatic conditions of a rainforest, are often considered to be the ideal conditions in which to grow ferns and for most of the indoor ferns derived from tropical regions this does apply. One should not forget, however, that ferns occur all over the world. Just think of the indigenous European species, like lady fern (Athyrium filix-femina), male fern (Dryopteris filix-mas) or hard fern (spicant).
Ferns will also colonize areas where you would never expect to find representatives of this plant group. Different species are distributed as far as sub-arctic regions, for example maidenhair spleenwort (trichomanes) or Adiantum pedatum. Others are found growing in particularly exposed positions on rocks, for example, Ceterach officinarum. Even in regions with hot, dry seasons, you will still find ferns like Davallia denticulate which manages to survive the periods after its leaves have dried up by forming rhizomes. Exactly the opposite type of arrangement has been adopted by floating ferns like Salvinia or Azolla which live on the surface of water.
Firmly anchored in the ground or high in the air
The indigenous European ferns grow either on the ground (terrestrial) or in trees (epiphytic).
The ground dwellers often occur along the banks of streams or rivers, around springs and among rocks. This shows that they prefer moist, though not wet, positions that are characterized by high humidity and slightly filtered light, important indicators as to the kind of care they require when indoors. One example is maidenhair ferns (Adiantum).
The epiphytes colonize tree trunks and the forks of branches and therefore can manage with very little or compost. They require conditions of high humidity and frequent rainfall to supply their water and nutrients. This elevated position also ensures that they receive adequate light, even in a tropical rainforest, another factor which needs to be taken into account when caring for them, Examples include staghorn ferns (Platycerium) and bird’s-nest fern ( nidus). Both species have evolved funnel-like leaves that are able to catch falling twigs and leaves which, over a period of time, will develop into a little pocket of humus. Epiphytes can also be grown in pots but you will have to make quite sure they are in very loose, coarse compost. Some types of fern can grow both as terrestrials or as epiphytes and thus prove to be very flexible with respect to their position. Among these are included many sword fern species (Nephrolepis).