Hard water fern
| Hard water fern | |
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| Hard water fern along the Huon Pine walk near Tahune AirWalk, Australia | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pteridophyta |
| Class: | Pteridopsida |
| Order: | Athyriales |
| Family: | Blechnaceae |
| Genus: | Blechnum |
| Species: | B. wattsii |
| Binomial name | |
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Blechnum wattsii Tindale |
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| Synonyms | |
Blechnum wattsii or the hard water fern is a common terrestrial fern growing in rainforest and open forest. Often seen near creeks in much of south eastern Australia, including Victoria, Tasmania (and King Island), South Australia, New South Wales and Queensland. The Blechnum wattsii was named for Reverend William Walter Watts (1856-1920). Reverend Watts was considered an authority on mosses and ferns and has more than 30 species named for him. Common names by which B. wattsii may be called are hard water fern - from its stiff leathery fronds, leech fern - as forest workers often encounter leaches while working in clusters of these ferns, hard hill fern - from the fern's habit and habitat, and red cabbage fern - from the bronze-pink colour of the young fronds resembling cooked red cabbage.
The mature B. wattsii can grow from 30 cm to 125 cm tall, with large erect fronds. The fern can spread horizontally using scaled rhizomes, which have a creeping, branched habit. The family Blechnum exhibit distinctive dimorphic fertile and sterile fronds, which are easily identifiable. The mature sterile fronds are dark, dull green, and leathery and pinnate. Young sterile fronds are pink-bronze tinged until maturity. The pinnae are close together on a long stipe, with the lower pinnae only slightly shorter than the upper pinnae, and a long frond tip. The pinnae have a finely toothed margin, and are slightly stalked - not sessile. They exhibit conspicuous lateral veins, which are crowded and parallel. The fertile fronds are longer than the sterile fronds, and generally grow in the centre of the fern. Sori are continuous along the underside of each mid-vein and cover the majority of the underside of the frond. The pinnae are linear, long and coarse, with long membranous indusia which can be difficult to see in mature fronds.
Blechnum wattsii shows the typical life stages of a fern with distinct sporophyte and gametophyte stages. A distinctive feature of the Blechnums is the presence of separate fertile and sterile, photosynthetic fronds. The fertile frond produces numerous spores which are prolific and easily collected and propogated to mature plants. It takes around 4–6 weeks for the prothallus to form, and another 6–12 months for the first true fern frond to develop. Mature plants can also be divided from root stock, providing there is little disturbance to the parent rhizome. Natural division through injury of the underground rhizome may also occur as the fern ages and degradation takes place. Once propagated, B. wattsii requires moist sheltered and partially shaded conditions.
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Wikipedia