The common has several different types of acidic heath grassland, together with areas of bracken, scrub, woodland, streams and a pond. The rich butterfly and moth fauna includes several uncommon species. It is in this area of the middle Sussex
Low Weald that the old
clay land community of herbs and sub-shrubs, grasses and sedges, on the spectrum from marsh to dry slope, is at its most complete. The Country Park is well known for its spring time display of bluebells, but unlike most bluebell displays that are usually protected by a leafy tree canopy, here the bluebell are sheltered by bracken. There is still
petty whin,
meadow thistle,
bitter vetch,
saw wort,
dyer's greenweed,
heath bedstraw,
tormentil,
betony and
devil's bit scabious. There are also many orchids including
heath spotted and
common spotted orchid and a kaleidoscope of hybrids. It is one of the few truly native sites for
wild columbine flowers and
ling heather clings on. There are still rarities too including
narrow buckler and
adders tongue ferns,
pignut, and the little
heath milkwort. The commoners' Common is the only part where the character of the original common is maintained and there is still a sense of landscape-scale openness. The biodiversity of the western part survived the farmers intent on ploughing and fertilising the grassland in the decades following the second world war. Now the Commoners Association do important work to save the area's biodiversity. Cattle grazing and scrub control are systematic and regular and as a result the old vegetation is still intact. There is a mosaic of
tufted hair grass and
purple moor grass,
tormentil and
dyer's greenweed, with low clumps of
dwarf and
European gorses, some thorn scrub, and a few super-special 'lawns' of rare
marsh plume meadow thistle, with accompanying
least willow,
spring,
carnation and
glaucous sedges and
quaking grass. On the marshy winter grassland,
snipe are still visitors. In late summer large
serotine bats forage and the forest specialist's
Bechstein's and
Barbastelle bats are also present across both parts of the Common. On both the commoners' Common and the Country Park, the closely related sub-shrubs
Dyer's greenweed and
petty whin were host to dependant populations of at least seven rare micro-moths, which were the chief fame of the Common to
lepidopterists. Most, if not all of the micromoths, are now gone, but their evocative names, such as
large gold case bearer, the greenweed leaf miner, the
greenweed flat body, and the
petty whin case bearer, are remembered. Also gone are the rare
tawny and
flea sedges,
starfruit at the pond, and
silver studded blue and
small pearl-bordered fritillary butterflies. The
marsh fritillary is also gone despite many reintroductions attempts between 1960 and 1991. ==References==