CUTICULAR ANALYSIS AND ANGIOSPERM LEAF DIVERSITY FROM A MIDDLE EOCENE CLAY PIT, WESTERN TENNESSEE

A study was undertaken to document the leaf diversity and the associated cuticle. Western Tennessee contains numerous clay pits which often have well-preserved leaf floras. Sometimes the leaves are oxidized leaving only an impression of the leaf and its venation, other times the clay may be organic rich. One clay pit, the Miller clay pit, contained abundant organically preserved leaves. We want to prepare a catalogue of the leaf types and the cuticle associated with each of the leaf types. We have 828 leaf specimens in our collection from the Miller clay pit of western Tennessee. It is difficult to distinguish many of the leaf types because they are covered with loose fragments of cuticle that obscures the venation. Initially they have been divided into several leaf types according to shape, for example, elliptic, oblongate, linear, lanceolate and ovate shaped leaves. There are toothed, entire, and undulate leaf margins which also can be used to differentiate the leaf types. The specimens have well-preserved cuticle which show distinct and different epidermal features and stomatal types so that the leaves can be differentiated easily based upon the cuticular anatomy. This study was undertaken to document the leaf diversity and the associated cuticle preserved on these leaves. E W Berry identified over 470 species of plants from the middle Eocene sediments of the Gulf Coast. Only a fraction of those species of the Gulf Coast Eocene occur at any one locality. At the Warman clay pit we have identified 41 leaf species and at the Wilbank clay pit we have identified about 54 leaf species. The use of cuticular characters helps us to distinguish the Miller clay pit species so that we can know the diversity of leaf types present in this flora.