The most characteristic habitat of Barnes Common is dry acid grassland, dominated by fine grasses such as Red fescue, Sheeps' fescue, Wavy hair-grass and Early hair-grass. The flowering plants found in these areas are Sheep's sorrel, which forms a reddish carpet in spring, Cats-ear and the attractive lemon-yellow Mouse-ear hawkweed. If you are lucky you can also find Creeping willow, Ling, Sand spurrey, a few Harebells and some yellow Ladies' bedstraw. In some areas you can see the male form of the tiny Hair Cap moss Polytrichum juniperinum and the minute but very pretty Birdsfoot on some of the sandhills. One of the rarest and most interesting plants, which isn't known from anywhere else in London, is the Burnet rose, which has been known from the Common for over 300 years.
Other grassland areas have been previously managed for sports and contain a coarser but colourful mix of plants such as Ox-eye daisies, Common Vetch, Speedwells and Willowherbs, as well as less attractive plants like Thistles.
The natural tendency of any open grassland areas is to become invaded by scrub, and in many areas there is abundant gorse and broom, also tree saplings. In time these will revert to woodland, and many of the wooded areas on the Common are of quite recent origin. The most frequent trees are Oak and Birch, often with Holly, Hawthorn, Elder, Rowan and Wild cherry. There are also many planted trees including Red oak, Lime and Norway maple.
The Common used to be much wetter than it is now, and there are a few areas where you can still find Reeds, Purple Moorgrass, Lady's smock and Gipsywort.
In an area surrounded by houses and gardens there are also sure to be a few blow-ins - this is especially true of the old Goods Yard area south of the station, which has many of the large colourful plants of waste ground such as Goat's rue, Evening primrose, Yellow melilot and Michaelmas daisies. A similarly interesting mix of plants is found in the old Cemetery by the Rocks Lane car park, where among the planted shrubs and trees there are a number of self-seeded Cotoneasters.