Association of Epiphytic Fern Vittaria lineata with Moss Octoblepharum albidum on Palm Sabal palmetto in Southeast Florida, with Notes on Accompanying Fern Phlebodium aureum

Abstract. In southeast Florida an association between the shoestring fern (Vittaria lineata) and the pantropical moss Octoblepharum albidum is conspicuous on cabbage palm (Sabal palmetto) trunks. As determined from quadrat studies, for maturing sporophytes, but not for gametophytes and tiny sporophytes, the frequency of association exceeded that expected by chance. The positive association suggests the moss facilitates the fern sporophytes. Based on a literature review and on new observations, the structure of the moss and its intimate relationship with V. lineata roots is consistent with the moss serving as a water-retentive “mulch” for V. lineata. In different habitats V. lineata can associate alternatively with the moss Syrrhopodon incompletus, and it sometimes grows on decaying petiole-base remnants or in petiole-base axils with no moss association. The only vascular epiphyte competing with V. lineata locally is the fern Phlebodium aureum. The lengths of its leaf blades, but not those of V. lineata, correlate with the lengths of immediately adjacent S. palmetto petiole-stumps. Phlebodium aureum is prominent where the stumps are long, whereas V. lineata dominates in trunk regions having no or small petiole-stumps, where it usually associates with O. albidum.