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Floristic Composition

Allochthonous fossil-plant assemblages occur in sands of the Upper Coal member in channel-lag and point-bar deposits. Fossils recovered from the sands include abrasion-resistant seed cones of Larix, Picea, Pinus, and Metasequoia, and rarely, angiosperm fruits (e.g., Juglans) (Basinger 1991). In forested horizons, autochthonous leaf litter mats represent the ancient forest floors of poorly drained floodplains and associated swamps (Ricketts 1986, 1991; Basinger 1991). Megafloral remains in forest floor mats include fertile and vegetative remains of the dominant conifers Metasequoia and Glyptostrobus, and minor occurrences of Picea, Pseudolarix, Pinus, Betula, Alnus, Juglans, Chamaecyparis, Tsuga, Osmunda, as well as a few unidentified angiosperm taxa (Ricketts and McIntyre 1986; Basinger 1991; LePage and Basinger 1991a; McIntyre 1991).

The scarcity of pinaceous representatives (Larix, Picea, and Pseudolarix) relative to those of the Taxodiaceae (Metasequoia and Glyptostrobus) indicates the Pinaceae were uncommon constituents within Taxodiaceae-dominated depositional realm. Angiosperms are poorly represented in the swamp forests but, judging from fossils in the sandstones and siltstones, were apparently a significant component of the regional vegetation. The dominant taxa occurring in the flood plains include representatives of the Betulaceae, Platanaceae, Juglandaceae, Fagaceae, Ginkgo, and Metasequoia.