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.
Blechnum wattsii – Hard Water-fern – Underside Fertile Pinnae, which are narrow and covered in spore producing sori.
A typical spreading colony of Hard Water-fern – Blechnum Wattsii
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 where the pinnae are attached by a very sort stalk
Blechnum wattsii – Hard Water-fern – Showing a typical dark-green frond
Blechnum wattsii – Hard Water-fern – pinnae – Underside of pinnae, which are also attached to the stem by a very short stalk.
Blechnum wattsii – Hard Water-fern – Showing the narrow fertile fronds
Blechnum wattsii – Hard Water-fern – showing both fertile fronds (taller and narrower) and regular fronds.
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.
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 – Pinnae are attached to the stem by very short stalks.
The back of a fertile Soft Water-fern frond covered in spore producing sori
Blechnum minus – Soft Water-fern Growing in a typical situation adjacent to water.
Blechnum minus – Soft Water-fern new frond (Crozier)
Blechnum minus – Soft Water-fern a typical frond
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 seven different species of the fern genus Blechnum (Water Ferns) in Tarra Bulga National Park and with a bit of background knowledge it is relatively easy to tell them apart. This post will focus on the identification of Blechnum nudum (Fishbone Water-fern) and Blechnum cartiliagineum (Gristle Fern), which unlike the other 5 species both have leaflets (pinna) being directly attached to the regular fronds by a broad base. The easiest way to tell them apart is by their fertile fronds.
Blechnum nudum (Fishbone Water-fern) is usually found in clumps in wet forest and gullies, it is reasonably common around Tarra Bulga.
Blechnum nudum – Fishbone water-fern
Blechnum nudum – Fishbone Water-fern, showing the underside of the leaflets (pinnae) which are a paler green and are attached to the frond by a broad base. The shaft of the frond (rachis) is often a shiny black colour.
Blechnum nudum – Fishbone water-fern, Showing the finer fertile fronds at the front and regular (Barren fronds) behind.
Blechnum nudum – Fishbone water-fern, showing fertile fronds which are different to the barren ones (which don’t carry spores)
Blechnum nudum – Fishbone water-fern
Blechnum cartiliagineum (Gristle Fern) is less common in Tarra Bulga and is more commonly found in gullies or sheltered spots at lower elevations downstream from the park.
Blechnum cartilagineum – Gristle-fern
Blechnum cartilagineum – Gristle-fern, Underside of a fertile frond showing bands of sori either side of the mid-vein.
Blechnum cartilagineum – Gristle-fern, also has leaflets attached to the rachis by their broad base.
Blechnum cartilagineum – Gristle-fern, The paired pinnae (leaflets) towards the base are separate and point downwards.
Blechnum cartilagineum – Gristle-fern, showing the lower stem (Stipe) which is grooved and has black scales.