Over 100 taxa of bryophytes have been recorded with the best diversity linked to the damp wooded areas of the botanic garden as well as the calcareous flushes along the shoreline of the Menai Strait. The Paxton Cascade, a natural waterfall embellished by 19th century landscaping boasts a number of thalloid liverworts such as Pellia epiphylla and P.endiviifolia, Conocephalum conicum and C. salebrosum. The tiny leafy liverwort Colura calyprifolia, a southern species which is spreading, is noteworthy on old apple trees.

Another leafy liverwort but much larger, Plagiochila asplenioides forms a lush emergent carpet beneath willow and birch in wet woodland in the central part of the wooded area while the general abundance of epiphytic pleurocarpous mosses reflects the humid nature of the woodland overall. Hookeria lucens a delicate, liverwort-like moss with strikingly large leaf cells visible to the naked eye, is quite widely distributed in damp shaded spots. There are one or two small colonies of Sphagnum palustre and a hornwort, Phaeoceros laevis can be found colonising damp gravelly areas by the glasshouses. The floating thalloid liverwort, Riccia fluitans is an interesting fairly recent addition, found in quantity in some years in the original garden pond.