Mycorrhizal association of the extinct conifer Metasequoia milleri

Vesicular-arbuscular (VA) mycorrhizas are described from anatomically prese rved roots of the Middle Eocene taxodiaceous conifer Metasequoia milleri, a nd compared to those of the living species M. glyptostroboides. Virtually i dentical VA mycorrhizal structures occur in the root cortex of both species , where they conform to the Paris-type. Coiled hyphae are most common withi n cells of the inner cortical region, and these produce numerous, highly br anched arbuscules. Close similarity of fungal position and structure within roots of the living and fossil Metasequoia species demonstrates that modem Paris-type VA mycorrhizal associations characterized taxodiaceous conifers by the early Tertiary.