A tiny fern which grows amongst limestone rocks and walls throughout Europe and far beyond in Asia carries this weird name. It is pronounced 'seterak'. Almost every book which mentions the plant uses it, also usually giving in British books the more easily understood 'rusty-back fern'. Like all ferns it has no flowers and no seeds. It reproduces by scattering spores which are formed on the underside of the fronds. These and the protective scales which cover them are in colour, rusty, and so it gets its name. The spores do not directly grow into new fern plants. They make a webby green structure rather like an alga or slimy pond weed of a small size. This produces female and male organs. The male organs produce sperm which swim, very much like the sperm of animals, in a film of water to the egg cells and from that fertilisation comes the adult fern plant. This life history as in all ferns, forces the plants to begin life at least, in damp places, even if the adult plant can withstand dry conditions. So the rusty-back fern grows out of damp cracks between the rocks. When full grown, the fronds will in a drought, dry and curl up. The sides curl towards the centre so that each frond looks like a brown stick of cinnamon. But when the rains come they will unfurl again. Ferns have almost no pests and I am not sure that anything eats them. Yet this plant has been called 'a great favourite of the mules' by a French author Hardouin (died 1729) . I took a nibble and found that the dried plant had quite a pleasant nutty taste. I did not swallow!
This brings me to the curious name - ceterach. Once again we have a herb with identical French and English names dating back to the early middle-ages and probably even before that. The Islamic physician Avenzoar of Seville, Spain, who lived about 1040 describes a potion using this plant to cure diseases of the spleen. This use is also mentioned by Pliny (the Roman died AD 79) but he calls the plant Hemionion. The Arabic name persists today, but still we do not know what the name signifies.
There are two species of fern in the picture. That to the right is the ceterach. On the left is the 'maidenhair spleenwort'. The word 'spleenwort' may be used for either, for the idea that these plants cure disorders of the spleen has been transferred to various ferns of similar appearance.
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