Of just under 1000 species of bryophyte known in the British Isles, 597 are recorded in the Inner Hebrides. This diversity of species is due to several factors: the suitability of the climate for bryophyte growth, the rich variety of bryophyte habitats and the presence of several phytogeographical elements in the islands.
Bryophyte species occur in varying numbers in almost all habitats from the spray zone at high water mark to the tops of mountains. Compared with the Outer Hebrides and the adjacent mainland, certain bryophytes are absent from the islands. This is largely due to the scarcity of dune slacks in the Inner Hebrides, and the poorer development of high mountain habitats.
Examples are given of a number of typical Inner Hebridean habitats together with their characteristic bryophyte species.
Naturally the Inner Hebrides are rich in species with an oceanic distribution in the British Isles. These are analysed into groups based on their world distributions. A number of species with strongly disjunctive distributions are thought to be Tertiary relicts in the British flora.
A list of the bryophytes recorded in the Inner Hebrides is appended giving presence or absence in each island or group of islands.