This small nature reserve on the eastern edge of the borough contains rough grassland, scrub, developing woodland and a short section of a very old hedge. The River Quaggy runs past the eastern edge of the site.
Open access throughout the year.
Much of the nature reserve actually lies in a former ox-bow, where a meander of the river became cut off to form a crescent-shaped lake, which gradually silted up.
While ox-bows often form naturally long meandering rivers, this one was created deliberately when the river was straightened as part of a flood alleviation scheme following the disastrous floods of 1968.
There is now more or less no trace of wetland habitat remaining on the site, and the river is encased in a 'concrete straight-jacket', preventing any future meandering.
The site was once used for gathering a hay crop for use on a nearby farm. The land was subsequently used for allotments, but these were eventually abandoned and the land reverted to semi-natural grassland and developing scrub. Sydenham Cottages, which give the site its name, are located off Marvels Lane; they are over 150 years old. They are passed on the way to the reserve.
Although not particularly botanically diverse, the meadow supports a good range of common butterflies, as well as field and meadow grasshoppers and Roesel's bush-cricket. In addition to the resident butterflies, a clouded yellow, a very scarce migrant in London, was seen here in 1996. Two common but impressive-looking bugs which can often be found here are the green shield bug (Palomena prasina) and the hawthorn shield bug (Acanthosoma haemorrhoidale).
Beside the entrance to the reserve is a hedge of hawthorn (including two hybrids between common and Midland hawthorns) with a little blackthorn. Several mature oak, ash and field maple trees emerge from the hedge, including a very fine old pollarded oak. Two other magnificent oak pollards were sadly felled during the building of Alice Thompson Close.
A ditch, marking the former course of the river, runs along the base of the hedge. Hairy St John's-wort, a scarce plant in London usually associated with scrub on chalk, was found here in 1999; it is known from nowhere else in Lewisham.
The old emergent trees and the ditch suggest that this is a hedge of considerable antiquity. A further section of this hedge, opposite the old cottages, contained several Midland hawthorns, usually a good indicator of antiquity; this was destroyed and replaced by a new hedge when Alice Thompson Close was built in the early 1990s.
Behind the hedge is an area of scrub and developing woodland, with damson and goat willow beneath mature oaks. The shrub layer has been supplemented by recent planting of hawthorn, hazel and field maple. Beneath these grow bramble, raspberry, cow parsley and ivy. There is a similar but smaller area of woodland and scrub on the opposite side of the site. The brambles and raspberry bushes produce plenty of fruit for avian and human visitors to the reserve.
Between these woodland areas, and occupying most of the middle of the site, is a large meadow, which is cut annually in late summer. The sward is rather rank and dominated by false oat-grass, with tall perennials such as mugwort, fennel, hogweed, nettles and thistles.
A substantial colony of stone parsley, a rather uncommon member of the carrot family, grows on the eastern edge of the meadow. This tall, slender umbellifer smells strongly of petrol if the leaves are crushed.
In shorter areas of grass, common vetch, black medick, yarrow and goat’s-beard can be found. The last named is sometimes called 'jack-go-to-bed-at-noon', because its yellow, dandelion-like flowers close up in the afternoon.
The reserve is owned and managed by the Council's Nature Conservation Section and there is open public access from Alice Thompson Close, which was built in the early 1990s.