Epiphytic ferns of the forest

Skyrail Nature Diary: August 2007

Australia’s World Heritage listed Tropical Rainforests are home to an amazing diversity of plant life, boasting over 2,300 different species from 195 families.

This month, we are going to look at a specific selection of plants known as epiphytes. Epiphytes are plants that grow on other plants, but are not parasitic.

This means that unlike parasitic plants, such as mistletoe, epiphytes harvest their nutrients from the surrounding elements including air, rain and falling leaf litter, without doing any harm to their ‘host’ plant. There are woody-epiphytes which are rooted into the ground, such as strangler figs, and non-woody epiphytes, like orchids and ferns.

Epiphytic ferns are one of the most common features in rainforests: they grow (sometimes prolifically) on the trunks and limbs of trees, as well as on rocks and the forest floor. In this edition of Passport to Cairns, we will take a closer look at three: Bird’s Nest Fern, Basket Fern and Common Tassel Fern.

The Bird’s Nest Fern (Asplenium australasicum) is a majestic plant, which is commonly seen at various levels throughout the rainforest. Its large fronds grow from a central point fanning outwards: this creates a funnel which helps to collect rainwater and falling leaves.

The Basket Fern (Drynaria rigidula) is one of the most massive and abundant epiphytes in the rainforest. Characterised by its two very different frond types, this fern grows around tree trunks and limbs (it can also be found on rocks and the forest floor) in a basket-shape.

The Basket Fern’s lower fronds are brown and papery; they interweave to create something of a ‘base’ or basket for the plant. This self-contained catchment system has a dual purpose: firstly, it catches rainwater and falling leaf litter, which are mulched to create nutrients for the fern, and secondly, it protects the young leaflets of the larger foliage fronds. The foliage fronds are feathery and green; they can grow up to two metres long and provide the photosynthesis services for the Basket Fern.

Last, but certainly not least, we look at the Common Tassel Fern (Huperzia phlegmaria). This is the most primitive fern in the forest and belongs to the ‘club moss’ family, which first appeared more than 300 million years ago and grew as large as trees.

Although the Common Tassel Fern has since reduced in size, it is still a stunning example of its origins, with its cascade of forked stems spiralling up to one metre away from its base.

Although it can be found widely through Asia, the Pacific and Africa, in Australia, the Common Tassel Fern is most likely found in the wet tropical rainforests of Tropical North Queensland, growing up to altitudes of 1,000 metres.