A pyritized twig resembling stems of the family Celastraceae is described f
rom the Eocene London Clay Formation of south-east England. This specimen i
s assigned to the form genus Celastrinoxylon (Schenk) Krausel 1939. The fos
sil has been studied by reflected light and scanning electron microscopy. T
he specimen is significant as it represents the first record of this family
within the London Clay wood flora. (C) 1999 The Linnean Society of London.