Photos - Ferns

Giant maidenhair fern, Asplenium formosum, regenerates prolifically on the near-vertical banks of Ourimbah Creek. These vertical walls are periodically renewed when there is above-average rain that saturates the silt of the banks. In this waterlogged state, the bank is prone to slip and expose a fresh cliff of earth above a lower terrace.

The spores of birds nest fern, Asplenium australasicum, germinate on tree trunks and on rocks, but only in seasons of frequent rains and mists. They are vulnerable to drought when small, but by the time they get to this size they can withstand long periods without rain. This is partly due to the way the leaves channel even a few drops of water into the centre of the plant. Falling leaves are also concentrated in the centre, where they rot and release their nutrients to the fern.

This lacy wedge fern Lindsaea microphylla grows on the embankments supporting the freeway that borders our site. Here it is growing intermixed with the straplike leaves of lomandra.

Above is another fern that grows on trees and rocks rather than in the ground - the elkhorn, Platycerium bifurcatum. The ones on our site are difficult to see, because they are generally perched high in the canopy. It needs more light than the birds nest fern and so tends to die if the canopy above it becomes too dense.

The steep clay embankment supporting Ourimbah Creek Road was originally a wilderness of weeds and garbage, but now is a seedbed for all kinds of interesting plants. Here is a young plant of Blechnum ambiguum growing on the near-vertical walls of the creek that issues from the road drain.

Above is a close-up of the underside of the austral lady fern, Diplazium australe. This species has spread to our site during the wet years of 2010-11, presumably from refuges in the gullies of the hills that surround us. Mature plants form a short trunk, but it is much smaller than that of the Cyathea tree ferns.