OCCURRENCE AND DISTRIBUTION OF PTERIDOPHYTES IN PARTS OF LAGOS AND OSUN STATES
Ferns make up an important component of tropical pteridoflora and serve important functions in ecosystem processes. The relative occurrence and distribution of ferns within the wetland area of Lagos and Osun States were studied with the aim of documenting the pteridophytic flora and habit in these areas. Four non-contiguous quadrats of 10 m x 10 m were established in each of the five study sites in consideration of the distribution pattern of the plants to be sampled. Non-random selective method was also adopted where the quadrats were preferentially located by sight to ensure that at least one individual pteridophyte was present in each quadrat. After sampling, the species were subsequently identified using reference collections at the herbaria of Forest Research Institute of Nigeria (FRIN) Ibadan, Oyo State and University of Lagos. A total of 16 species of ferns belonging to 11 genera and 9 families were recorded. On their distribution, the two study sites in Osun State recorded the highest number of species (11 species, 68.75%) most of which appear to be uncommon species while the three sites in Lagos recorded only 4 species (25%) which are relatively common species. In general, there were 46% terrestrial species, 32% lithophytes and 22% epiphytes in all the five sites studied and species diversity and evenness in Osun and Lagos States were 1.819, 1.444 and 0.4742, 0.7064 respectively. The occurrence and distribution of the pteridophytes varied considerably between the two sites studied, as only one species was common to both sites. This may be attributed to microhabitat, anthropogenic factors, climatic conditions and the nature and states of vegetation and thus there is need for in-situ and ex-situ conservation of fern species in Lagos and Osun States in order to avoid the loss of these rare species and biodiversity at large.