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New advice: keep your powder wet
Conservation of endangered species has many facets ranging from prevention of habitat loss to maintenance of what is loosely called germplasm. It is this latter aspect that is the concern of Luis Quintanilla et al. (Madrid and Santiago de Compostela, pp. 461-467). They are working with five fern species (Culcita macrocarpa, Dryopteris aemula, D. corleyi, D. guanchica and Woodwardia radicans) that occupy particular habitats in the sub-tropical islands of the eastern Atlantic and in parts of southern Europe, including regions of Spain. The ferns are rare because of their habitat and geographical requirements. They are also under threat because in mainland Spain their habitat is considered ideal for commercial growth of Eucalyptus globulus. The authors have studied the germinability of the spores of these ferns in relation to storage conditions to optimize conditions for germplasm maintenance. In comparison with knowledge of angiosperm seed physiology, very little is known about fern spores. Some attempts at storage of fern spores have followed the practice used for many crop plant seeds, i.e. they have been stored under very dry conditions. However, what may be good for seeds may not be good for spores. In all five species, wet storage preserved spore viability better than dry storage, although in the three Dryopteris species, dry storage was nearly as effective as wet storage. Temperature was also important: in wet storage, 20 degrees C was a more effective temperature than 5 degrees C (but spores of W. radicans actually germinated at 20 degrees C in darkness), whereas in dry storage the reverse was true. Wet storage at -20 degrees C was lethal for spores of all species whereas dry storage at this temperature had variable effects but was only totally lethal for C. macrocarpa. The authors have thus made a good start in defining optimum conditions for preservation of spore viability in these threatened species.
Professor J. A. BryantUniversity of Exeter, UK
j.a.bryant{at}exeter.ac.uk
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