The coal bearing Oligocene sediments exposed in the Makum Coalfield, Assam contain rich assemblage of mega-plant remains. Out of a large number of leaves and fruits collected from the associated sediments at Baragolai. Ledo-Tirap and Tipongpani collieries of the Makum Coalfield, 24 species of dicotyledonous taxa have been identified. Of these, 22 are represented by leaves belonging to the genera Saccopetalum (Anonaceae); Calophyllum, Garcinia, Kayea (Clusiaceae); Pterygota (Sterculiaceae); Santiria (Burseraceae); Heynea (Meliaceae); Nephelium (Sapindaceae); Lannea, Mangifera, Parishia (Anacardiaceae); Rhizophora (Rhizophoraceae); Terminalia (Combretaceae); Memecylon (Memecylaceae); Avicennia (Avicenniaceae); Alstonia (Apocynaceae); Myristica (Myristicaceae), Apollonias (Lauraceae) and Bridelia (Euphorbiaceae). The remaining two taxa are based on fruit/seed comparable to those of Dalbergia and Entadu of Fabaceae. The distribution pattern of comparable modern taxa of fossils and keeping in view the great amount and variety of plants preserved in the sediments, it is inferred that thick tropical evergreen to moist deciduous forest existed in this part of northeast India during Oligocene. Occurrence of Avicennia, Rhizophora and Terminalia catappa suggests deltaic, mangrove or agoonal deposition of coalseams and associated sediments in the Makum Coalfield.

Five petrified woods showing affinities with Hopea of the family Dipterocarpaceae, Berrya of Malvaceae, Eucalyptus of Myrtaceae and Diospyros of Ebenaceae are systematically described from the Cuddalore Sandstone Formation exposed near Puducherry, Tamil Nadu. Among them, four are new species, namely Hopenium tertiarum sp. nov., Berryoxylon cuddalorensis gen. et sp. nov., Eucalyptoxylon cuddalorensis sp. nov. and Ebenoxylon cuddalorensis sp. nov. Their modern counterparts indicate the existence of wet evergreen forests in the region during the depositional period. However, most of the modern comparable forms of the fossils are absent from the region today and found in the Western Ghats and northeast India having equable climate thereby indicating a change in the climatic conditions in the eastern coast of south India since the late Cenozoic.

The description and affinity of the fruiting axis Callislemonites indicus Bande, Mehrotra & Prakash 1986 reported from the Deccan Intertrappean beds, Shahpura in Mandla District, Madhya Pradesh have been revised. It is an incompletely preserved cast of the fruit with well-preserved seeds and shows close resemblance with that of Musa instead a fruiting axis Callistemon-Melaleuca as suggested earlier. It is very similar to the fossil fruit Musa cardiosperma Jain which was described from the Deccan Intertrappean beds of Mohgaonkalan, Chhindwara District and hence has been placed in the same species. This provides further evidence of the wider distribution of Musa in central India during Late Cretaceous- Early Palaeocene time.

Gymnosperms, the most dominated group of plants during Mesozoic, were meagerly represented in Indian Tertiary flora. The Tertiary gymnosperms occur in the form of petrified woods, cones and leaf impressions, besides pollen referable to the families Podocarpaceae, Araucariaceae and Cycadaceae. Until Late Cretaceous-Early Palaeocene the gymnosperms were widely distributed in the Indian peninsula. However, during Tertiary they declined to such an extent that towards the close of Pliocene Araucariaceae totally disappeared from Indian sub-continent. The podocarpaceae too, is now on the verge of extinction as it occurs in the restricted areas in northeast India and Nilgiri Hills in southern India. The cause of decline of these tropical gymnosperms and advent of the northern temperature members in the Indian subcontinent during Tertiary are discussed.