Psilotum nudum is an epiphytic fern belonging to the Family Psilotaceae. In Bali Botanic Garden, this plant grows on the stem of tree fern, but not all stands of tree fern become phorophytes for P. nudum. Studying P. nudum ecology in the Bali Botanic Garden is crucial in conservation efforts. The research was conducted in the Bali Botanic Garden area, using field observation methods on tree ferns located on the right and left of the main route of the garden. The data collected include tree fern species as hosts, the number of P. nudum individuals (clumps), P. nudum growing height and associated plants. The results showed that P. nudum was only found growing on one species of tree fern (phorophyte), Alsophila orientalis. Psilotum nudum is also associated with 43 species of plants. The most common plant species are Davalia denticulata (10.6%), Asplenium nidus (8.13%) and Dischidia sp. (6.91%). Host tree fern height has a weak but insignificant correlation with the number of P. nudum individuals (r = - 0.14, p = 0.5). The higher the Alsophila tree, the fewer P. nudum individuals were found. Host tree fern height was weakly correlated with the number of associated plant species (r= 0.24, p= 0.22). This data helps complete ecological data on collection plants that can be a reference in their development and cultivation efforts.