One of the trickiest groups of Ferns to identify locally are a group of Ground ferns in the Genus Hypolepis. There are three different species recorded in the park but I have only ever found two of them which are Hypolepis glandulifera (Downy Ground-fern) and Hypolepis rugulosa (Ruddy Ground-fern). Without looking carefully these ferns can be mistaken for Bracken because they have a similar growth habit with fronds popping up from a spreading underground rhizome.
Hypolepis rugulosa (Ruddy Ground-fern) seems to be more common locally at higher altitudes in the Park (e.g. Wet Forest areas around Balook). It seems to like disturbed areas at the sides of roads and tracks. Its main feature for identification in the field is the reddy-brown colour of the frond stems (Stipes).
Underside of fertile fronds showing arrangement of sori.
Close up of underside of pinnule. Showing little flap with a few hairs next to the sori.
Hypolepis rugulosa – Ruddy Ground Fern
Topside of pinnae which are slightly harsh.
Ready brown frond stem (stipe) with small hairs.
Frond showing red-brown coloured stem (Rachis)
Base of frond (stipe) where it comes out of the ground, Chestnut brown with hairs.
New frond (crozier) not stickly like Downy – Ground-fern.
Red-brown frond stem (Rachis)
Hypolepis rugulosa – Ruddy Ground Fern
Hypolepis glandulifera (Downy Ground-fern) I have found mostly at lower altitudes, especially along waterways (e.g. Tarra River and Macks Creek). Its frond stems (Stipes) are usually a pale green colour. It usually has lots of fine hairs along the stems and the new fronds are often sticky to the touch as a result of the small glands on the tips of many of the hairs. If you have a hand lens or use a digital camera with a macro setting you can see that there is a little triangular tooth close to the sori on the underside of fertile fronds. This fern was formerly known as Hypolepis punctata.
Close up of frond stem (stipe) with soft hairs, some of them with glandular tips.
Sori have a small tooth shaped flap protecting them. (note this photo is magnified)
New frond, which is sticky to the touch because of the soft glandular hairs.
Showing the base of the fronds. Mostly a light green colour.
Underside of a fertile frond, packed with sori.
Pinnules usually have rounded tips.
Hypolepis muelleri (Harsh Ground-fern) is also listed in Park’s flora records for the but I have yet to find any. It can be identified by the presence of tiny hairs growing in the Sori on the underside of the fertile fronds.
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 – Showing the narrow fertile fronds
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 – pinnae – Underside of pinnae, which are also attached to the stem by a very short stalk.
Blechnum wattsii – Hard Water-fern – showing where the pinnae are attached by a very sort stalk
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 – 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.
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 Growing in a typical situation adjacent to water.
The back of a fertile Soft Water-fern frond covered in spore producing sori
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.