Little, Stefan A. , Stockey, Ruth A. .
Reconstructing fossil Lauraceae: the importance of whole plant concepts.
NUMEROUS remains, putatively assigned to Lauraceae, are known from the Middle Eocene Princeton Chert. Inflorescence architecture is monotelic with oppositely-arranged, cymose lateral units. Each cymose unit has at least three flowers: a terminal flower, and two oppositely arranged penultimate flowers. Additional flowers are present on some lateral subunits. Inflorescence architecture is typical for that in several genera of Lauraceae. Flowers are pedicellate, hermaphroditic, trimerous, with two whorls of tepals. Some non-terminal flowers are dimerous, but otherwise identical to trimerous flowers. Anthers lack trichomes, are bisporangiate and occur in three whorls. Filaments of the third androecial whorl each bear a pair of globose appendages, and an innermost, fourth whorl of staminodes is lacking. The outer two whorls of stamens are introrse, and the third, inner whorl is extrorse. The gynoecium is a single carpel with one pendulous ovule. Recent investigations have revealed evidence for the connection of the inflorescences to the fruits in a developmental series. The youngest fruits are found with attached floral remnants. Later stages show enlargement of the receptacle, thickening fruit wall, and the development of abundant sclereid clusters. Mature fruits are borne on a shallow cup-shaped receptacle, and contain one large seed. Fruits have an inner palisade layer with digitate cells and fleshy mesocarp. Fruit, floral, and inflorescence characters are unique and represent a new genus of Lauraceae. In isolation, the fruits or inflorescences would not have provided a suite of diagnostic characters. Therefore, this study highlights the importance of whole plant concepts for Lauraceae, a family with several poorly understood generic concepts.
Log in to add this item to your schedule
1 - University of Alberta, Department of Biological Sciences, Biological Sciences Centre, Cw 405, Edmonton, Alberta, T6G 2E9, Canada
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 3:15 PM