XVI International Botanical Congess

Evidence for adaptations to aquatic environments are rare in Eocene deposits except for one remarkable biota preserved in the Princeton chert of British Columbia. This site has yielded some of the best preserved and most complete ferns, conifers, angiosperms and their associated fungi known in the fossil record. Plant organs are preserved as permineralizations and all parts of the plant life cycle are known including delicate flowers containing pollen and embryo tissue for some taxa. The largest numbers of plants preserved are those with adaptations to aquatic environments. Aerenchymatous tissues in the cortex of rhizomes, petioles and fruits, opercula and palisade layers of tightly packed sclerenchyma in seeds, protoxylem lacunae and reduced vascular systems in petioles are known for several taxa. The presence of aquatic animal fossils at the sit and the affinities of many of the plants found here with well-known aquatic plant families help to strengthen the interpretation of these as aquatic plants that were preserved in situ.