Florae Malesianae Precursores XLIV. The fern-genus Elaphoglossum in Malesia, with descriptions of new species

During the preparation of a monograph of the genus Elaphoglossum for Flora Malesiana, I have recognized twenty-three new species; these are here described. I take this opportunity also for publishing a few comments on the genus. In both these matters I wish to acknowledge the work of Mr P. R. Bell, who began a series of morphological studies of Elaphoglossum some years ago, primarily based on species he had seen in tropical America (see Bibliography); Mr Bell also made a quite intensive study of scales and other characters of some species from Malesia, and has handed over his notes for my use; two of the species here described as new were so recognized and named by him. Most of the new species here dealt with are from New Guinea, which indoubtedly has a much larger and more varied representation of the genus than any other part of Malesia. The most important New Guinea collections are those of Dr. L. J. Brass, on successive Archbold Expeditions. In spite of the wealth of this material, we really need much more if we are to have a satisfactory understanding of the genus in that area; several of the new species are described from single collections, and such may not give a true idea of the possible range of variability (due to age of plant and to environmental factors) within a species. As I know from personal experience, Elaphoglossum plants, growing on treebranches with other epiphytes, are easy to overlook; their simple fronds are often very like leaves of orchids when seen at a distance. Probably all species of Elaphoglossum produce fertile fronds seasonally, presumably as a result of a climatic stimulus, but the nature of the stimulus has not been proved. By analogy with behaviour of other ferns which I have had under frequent observation, I think it most probable that a spell of drier weather (which quickly affects epiphytes) is the stimulus, and probably different species respond in different ways. Though most species are epiphytes, a few are reported as terrestrial, in some cases perhaps casually so; one ( E. resiniferum) is reported as growing on wet rocks in a stream-bed. Collectors usually do not make specimens from sterile plants, but good sterile material is usually quite distinctive. I wish I had myself realized this when I had the opportunity of seeing these plants in their native environment. Distribution. The genus as a whole is pantropic, and is believed to comprise more than 400 species, the majority in the New World. The present study of Malesian species brings the total in Malesia to almost 50, which indicates that the genus is more diversified in this region than in any other part of the Old World, though undoubtedly more species of mainland Asia remain to be recognized. A few Malesian species are quite widely distributed [E. angulatum (Bl.) Moore in Reunion, Ceylon, and throughout Malesia; E. callifolium (Bl.) Moore throughout Malesia and apparently to Fiji], but many appear to be rather local; however, it may be that further collections will show that some of the latter are more widely distributed than is at present known. My recent studies have indicated such cases, which will be reported in Flora Malesiana.