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Nephrolepis cordifolia (L.) C.Presl 1846
pronounced: neff-roh-LEP-iss cor-dih-FOH-lee-uh
(Nephrolepidaceae – the sword fern family)
common name: Sword Fern, Fishbone Fern
Nephrolepis is derived from the Greek νεφρος (nephros), the kidneys (referring to the shape of the sori), and λεπις (lepis), a scale (referring to the scales on the rhizomes and stolons); cordifolia is from the Latin cor (cordis), the heart, and folium, a leaf. The species is native to north-eastern Queensland, and is considered naturalized on the central east coast of NSW. It has been introduced to many other parts of the world, and has often become an invasive species in such places, especially in New Zealand and Florida. Its exact native range is obscure, partly because it has often been confused with other similar species. It has also been “discovered” quite a few times: the Kew Plant List gives 6 synonyms, and Wikipedia gives 10. In its natural environment, it can be found growing in rocky areas, or on rainforest margins, or as an epiphyte on palm trees in the wetter parts of Queensland. Often planted as a space filler around the bases of trees in tropical gardens, it soon fills the allotted space, and expands rapidly. It is often a weed of parks, gardens, roadsides and suburban bushland. The plants photographed are growing around trees, or epiphytic on palms, in the parkland near the southern end of the Picnic Bay mall.
This fern, very common on Magnetic Island, has upright or drooping fronds, usually up to 50 cm long. It forms a network of creeping rhizomes, usually with slender and wiry stolons running along the surface of the ground as well. On the rhizomes it frequently produces fleshy spherical tubers, about 1.5 cm across. The rhizomes and stolons and the lower parts of the stipes are densely covered in glossy brown elongated scales. The fronds have a brownish stipe, and alternate pinnae. These pinnae are usually 10 – 35 mm long and 4 – 11 mm wide, but occasionally reach 6 cm in length. They have irregular margins, often crenate or crenulate, and are usually glabrous. The tips of the pinnae are relatively broad and somewhat rounded, and their bases are usually somewhat overlapping and slightly lobed on one side. The fronds tend to be a dull green in shaded areas, and a lighter green, even yellowish green, where it is sunny.
Numerous brown, reniform sori are evident on the undersides of mature fronds, and they contain the numerous spores by which the ferns reproduce. The sori are partially protected by a tiny reniform indusium, and they are arranged in two rows, one on either side of the midrib, half-way between it and the centre. Sometimes there are raised dots on the upper surface near the margins of the pinnae where the spores are pushing into the leaf from below. As well as reproduction from the spores, spread mainly by wind and water, the ferns also reproduce vegetatively from the rhizomes and the tubers, often through the disposal of garden waste.
Photographs taken in Picnic Bay 2014
Page last updated 28th January 2018