Tilia cordata is generally regarded as native in England and Wales but until recently the status of T. platyphyllos has been doubtful. In spite of a number of statements in local floras that T. platyphyllos can scarcely be other than native in particular localities (Painter 1889; Purchase & Ley 1889; Baker 1906; Hyde 1935), the apparent absence of fossil remains of T. platyphyllos in post-glacial deposits in Britain gave strong support to the view that the plant had reached even these sites recently and through the agency of man. However, this argument has lost its force with the demonstration of substantial quantities of pollen of T. platyphyllos in post-glacial deposits in Cambridgeshire (Clark & Godwin 1962) and Norfolk (Godwin 1968) and of both pollen and fruits in deposits of similar age in Warwickshire (Kelly & Osborne 1964). The sites in which T. platyphyllos has the strongest claim to be regarded as native are principally on cliffs or screes of limestone, dolomite or basic igneous rock. One group of localities is in the Welsh borderland, including the Wye valley, Breconshire and Shrop