Ferns: a touch of forest in your garden
The moist, dark places that Ferns prefer reflect their forest habitat, where the sunlight filters intermittently through the leaves, rarely reaching the ground, among the mosses that grow on dead or living tree trunks. And the internal structure of the Fern leaf, the mesophyll, displays their complete adaptation to these warm, wet places. The large intercellular spaces allowing for the huge evaporation which would damage other plants.
A cushion of Ferns
Most Ferns grow in soil very rich in the humus derived from the masses of leaves that have fallen from the surrounding trees. On a forest walk this almost allows you to bounce along as you stride through the rich carpet of dying and decaying leaves. However, some Ferns grow on other plants, mostly trees. While this occurs mainly in tropical regions, it can also be seen closer to home. Oak Ferns, for example, tend to choose a high place amongst the Oak canopy for a home and there are also small Ferns that grow on walls, usually old ones. The Cetera officinarum is very common in southern Europe where it grows on rocks in the full sunlight!
The ways in which Ferns grow can differ quite a lot. Many Ferns have rootstocks allowing them to spread rapidly, like the Beaker Fern for example, while others remain much smaller and do not have this invasive habit. And Ferns do not only differ in shape, but also in colour. Many Ferns have the most amazing autumn colouration, while Athryrium niponicum 'Metallicum' is sometimes called the Rainbow Fern because of its many fantastic coloursA good reason for having a Fern in your garden is that many of them are evergreens, like the Polystichum aculeatum.
- Ferns often have two types of leaves which may be quite different in shape. One type has the brown spore boxes while the other type does not. The former can even look like overblown flowers, as in Osmunda regalis, for instance.
- Ferns look their very best in spring when their new leaves are still all coiled up. As they develop they unroll themselves to reveal the fresh and vibrant leaf forms with which we are familiar and, on many types, hairs become clearly visible at this stage.
Of course, everything a plant does is aimed at keeping the species alive. And the flowering mechanism has been successful in making sure that seeds are spread (preferably not too close to the mother plant) to start a new life. Ferns however, do not flower, but have still managed to survive for millions of years. Their tactic is to form extremely fine spores in special, brown coloured, spore boxes on their fertile leaves. When ready, these spores are carried off by the wind to land in new areas where, if the environment is suitable, they will grow into a new plant.