Ferns and Fern Allies in the Canberra RegionBlechnum nudum - Fishbone Water FernBlechnum nudum is
by far the most common fern in fern gullies and boggy patches in mountain
creeks in the region. It is one of three common water ferns that grow
in these areas, often accompanied by B. minus (Soft Water Fern)
and B. wattsii (Hard Water Fern). It may grow as individual plants
but more often grows in large colonies, to the exclusion of any other
fern except tree ferns. The fronds grow in a rosette from an erect rhizome
which can form a short tree-fern-like trunk in old plants (see below).
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The
fronds can grow up to a metre long in this area. The pinnae are fairly
coarse, though softer than those of its cousins, B. minus and
B. wattsii, with narrower pinnae, usually no more than 1.2cm
(1/2") wide. This picture shows a plant with a rosette of sterile
fronds surrounding newly emerging fertile fronds. The fertile fronds
are shorter than the sterile ones and the pinnae are much narrower.
It is an attractive fern, very easy to grow, and extremely hardy, tolerating
both heavy frost and some direct sun. It does best when its roots are
permanently wet. 
The
image at left shows a mature B. nudum plant growing in a Dicksonia
antarctica grove in the Blue Range. It shows the treefern-like trunk,
around 0.5m (20") high. Most mature specimens show this behaviour,
though it is usually not obvious due to the accumulated debris of old
dead fronds.
