Christella dentata (Forssk.) Brownsey & Jermy.
Christella dentata is a small perennial fern, ranging from 0.25-0.8m high, with a widespread global distribution (Spooner,1997). It is widespread throughout Australia, however in Western Australia the species is confined to the far north of WA in the Kimberly region and is native to Australia (Spooner,1997). Some common names include; soft fern, Christella, Helecho and Downy Maiden (CABI,2013) (New Zealand Plant Conservation Network, 2013).
Throughout most of Australia, Christella dentata is considered a vulnerable species as it is restricted to small areas with a low number of individuals throughout Western Australia, Victoria, South Australia and the Northern Territory. However, it is widespread in New South Wales and Queensland. Also throughout many regions of the world it is still widespread.(CABI, 2013)
Under the Wildlife Conservation Act, for Western Australia this species has been categorised with a Conservation Code of Priority 2, indicating that Christella dentata is a poorly-known species, with only a few collections or sighting records (Department of Parks and Wildlife, 2013).
The Rhizome is short, grows along the surface of the ground, and is indistinctively erect or sub erect. Fronds vary considerably in length, usually 60-90cm long, are dark green in colour and consist of a soft texture. The stipe is 20-50cm long with short hairs. Lamina is egg shaped with a narrow end at the base, and is greater than 50cm; the pinnae; primary segment of the lamina, is in 15-25 pairs, basal in 2-4 pairs and is progressively reduce; the basal pinnae is 4-5cm long, with a strong ear like lobe pointing to the apex at the base of the pinnae; the largest pinna is 8-10cm long, 1.5-1.8cm wide, and indented halfway to two-thirds of the way of the midrib of the pinnule; the apex is gradually tapered to a point, pinnae lobes are slightly slanted with rounded tips: veins in 8 or 9 pairs; basal vein; which runs along the edge forms a network creating a vessel or opening to the short sinus membrane (membrane of depression between the adjacent lobes in a pinna); and acroscopic vein (facing towards the apex) passes to the side of the sinus membrane; the lower surface of rachis (midrib of the lamina or of a primary, secondary, tertiary pinna) with 0.2-0.4cm long hairs; hairs on the lower surface of the costae (ribbed) and costules (midvein of pinnule) mostly 0.2mm long; hairs on upper surface of costa greater than 0.5mm; hairs on upper surface of costules and veins are similar and scattered; hairs between the veins are thin, dispersed, very short and both stiff needle like and consist of a rounded apical cell. Sori; cluster of sporangia extends in the middle, except the lowest ones which sometimes touch those on veins from neighbouring costules; indusium which is the covering of the sorus, is thin with copious amounts of short hairs. (Bostock & Holttum, 1998)
Christella dentata is a relatively unknown species, found at latitudes between 35°N and 38°S varying in climates of tropical, tropical rainforest, tropical monsoonal, temperate, warm wet temperate and warm dry temperate (CABI, 2013).
There is believed to be two different forms in New Zealand, however the relationship between these two forms and whether they are both related is still unknown. This second form has been found in thermal areas and on Raoul Isand, and consists of erect or short creeping rhizome, instead of the long creeping rhizomes found on true Christella dentata.
Christella dentata is a relatively unknown species, with little literature available on the evolution of the species.
Christella dentata has a distribution described as a tropical cosmopolitan distribution; meaning it extends across most of the worlds tropical region (CABI, 2013). It was originally native to the old world tropics of Asia and Africa, as well as the temperate parts of Australia and New Zealand and was introduced into America in the sub tropical frost free regions . Christella dentata has also been recorded in many of the Pacific and Greek Islands. Christella dentata is found throughout Australia, and is widespread in Queensland and New South Wales. Though out the Northern Territory it is classed as being localised and only occurs in a small number of locations in South Australia, Victoria and Western Australia (The Alas of Living Australia, N.D). Within Western Australia there has been two locations where Christella dentata has been recorded, which are both in the far North West region of the Kimberly (Spooner, 1997). For more detailed distribution of Christella dentata globally visit: Invasive Species Compendium
Christella dentata mostly occurs in warm damp habitats, commonly wetlands, coastal wetlands, river banks, woods, open wet areas and forests and can tolerate various soil types. In Western Australia the species inhabits sandstone crevices and areas of sandstone rocks (Spooner, 1997). In other places around the world such as the Bahamas it has been found growing on limestone substrates and is tolerant to shade (CABI, 2013).
Christella dentata has been found to be a herbal medicine, as it has antibacterial properties from the alcoholic and chloroform extracts (Kumar & Kaushik, 2011).
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