Unique Southeast Asian peat swamp forest habitats have relatively few distinctive plant species GiesenW. WijedasaL. S. PageS. E. 2019 The peat swamp forests of Southeast Asia are often described as having a unique biodiversity. While these waterlogged and nutrient-poor habitats are indeed unique and include a distinct fauna (especially fish), the peat swamp forest flora is much less distinct and shares a surprisingly large number of species with other habitats. Out of 1,441 species of higher plants found in Southeast Asian swamps (from Thailand to Papua), 1,337 are found in the lowlands (< 300 m a.s.l.). Of these 1,337 species, 216 (16.2 %) occur mainly in lowland swamps, 75 (5.7 %) are shared with freshwater swamps and riparian habitats, 49 (3.7 %) are shared with heath forests, 7 (0.5 %) are shared with montane ecosystems, and 86 (6.5 %) are shared with a range of other lowland habitats. Of the 216 species (16.2 %) that occur in lowland swamps, 120 (9.2 %) are restricted to this habitat (which includes freshwater swamps), and 45 (3.4 %) are restricted to lowland peat swamp forests. Thus, more than 80 % (1,152 species) of the known peat swamp forest flora is common to a wide range of habitats, while 12.4 % (166 species) is composed of opportunistic pioneer or secondary forest species.