Another post in our series for people wanting to know more about the fern species in Tarra Bulga National Park and how to identify them. Here we look at two more species of Blechnum. Hard Water-fern (Blechnum wattsii) and Soft Water-fern (Blechnum minus).
Blechnum wattsii – (Hard Water-fern) is much more common than the Soft Water-fern at Tarra Bulga and is found in both Cool Temperate Rainforest and Wet Schlerophyll forest areas. It has tough dark green fronds, a key feature is that the lower leaves (pinnae) on each stem (rachis) are only slightly smaller than the others.
A typical spreading colony of Hard Water-fern – Blechnum Wattsii
Blechnum wattsii – Hard Water-fern – Showing a typical dark-green frond
Blechnum wattsii – Hard Water-fern – showing where the pinnae are attached by a very sort stalk
Blechnum wattsii – Hard Water-fern – pinnae – Underside of pinnae, which are also attached to the stem by a very short stalk.
Showing lower pinnae of Hard Water-fern at the top of the photo which are only slightly smaller than the ones on the rest of the frond.
Blechnum wattsii – Hard Water-fern – showing both fertile fronds (taller and narrower) and regular fronds.
Blechnum wattsii – Hard Water-fern – Showing the narrow fertile fronds
Blechnum wattsii – Hard Water-fern – Underside Fertile Pinnae, which are narrow and covered in spore producing sori.
Blechnum minus – (Soft Water-fern) is locally more restricted in its distribution and mainly confined to the banks of water-bodies. It’s fronds are a lighter shade of green and the margins of the pinnae are more undulating or wavy. A key feature of their identification is that the lower leaves (pinnae) on each stem is are much shorter than the rest and they are also widely spaced apart.
The back of a fertile Soft Water-fern frond covered in spore producing sori
Blechnum minus – Soft Water-fern – Pinnae are attached to the stem by very short stalks.
Lower pinnae of the Soft Water-fern, are much shorter than the ones along the rest of the stem and are more widely spaced apart, (the grass is covering up a another pair of pinnae even lower down the stem).
Blechnum minus – Soft Water-fern new frond (Crozier)
Blechnum minus – Soft Water-fern a typical frond
Blechnum minus – Soft Water-fern Growing in a typical situation adjacent to water.
Both species are dimorphic meaning that the fertile fronds that contain the spores are different to the regular fronds, for both of these species they are a lot more slender than the regular fronds.
There are four main species of tree ferns found in Tarra Bulga National Park, (along with many other fern species) The two most common you will see are Cyathea australis (Rough tree-fern) and Dicksonia antarctica (Soft tree-fern). The Soft Tree-fern is more common in the moister areas including the rainforest gullies while the Rough tree-fern is more dominant on the slopes. Once you get you eye in it is fairly simple to tell the difference between these two, the most obvious being by comparing the trunks. The Rough tree-fern has much of its trunk covered by the remains of broken off stems (Stipes) Which are rough to the touch, while the Smooth tree-fern is soft to the touch and is covered by masses of soft hairs which are actually roots. On this soft trunk other species of plants will often grow including tree and shrub seedlings, epiphytes and other ferns.