Before 1800 this whole area was part of the Great North Wood, bordering Sydenham Common. Little of these ancient woodlands remain. The trees in this reserve have recolonised the site during the past 170 years since the building of the railways and are defined as secondary woodland. Most of the older trees were cut back to ground level at least once during construction of the railway embankments, giving them a coppiced growth form (multiple trunks growing from a single
The trees are predominately pedunculate oak (Quercus robur), sessile oak (Quercus petraea), ash (Fraxinus excelsior), sycamore (Acer pseudoplatanus), with an understory of hawthorn (Crataegus monogyna), elder (Sambucus nigra), holly (Ilex aquifolium) and various fruit trees (Prunus sp.). There are also a few horse chestnut (Aesculus hoppocastanum), hazel (Corylus avellana) and yew (Taxus baccata). Silver birch (Betula pendula) is rare or absent, but it can be seen in abundance on the other side of the railway track on the more acidic soils of Garthorne Road Nature Reserve.
Most of the trees are covered in a dense growth of ivy (Hedera helix), which attracts many insects and birds. Old man’s beard (Clematis vitalba) also grows in abundance and is regularly cut back to prevent it completely shading out trees and shrubs. The woodlands support a rich herb layer, including wood avens (Geum urbanum), wild garlic (Allium ursinum), dog violets (Viola sp.), cow parsley (Anthriscus sylvestris) and many other wild flowers. Shrubs are regularly removed from some areas of the woodlands to form clear glades, which are particularly valuable for butterflies. The woodlands are important nesting and foraging grounds for many birds, and bats can be seen after dusk hunting for insects in the tree tops.
Butterflies include holly blue, comma, red admiral, peacock and brinstone.