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INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: A MIMOSOID INFLORESCENCE
Author(s) -
Crepet W. L.,
Dilcher D. L.
Publication year - 1977
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1977.tb11913.x
Subject(s) - biology , inflorescence , pollen , mimosoideae , stamen , botany , subfamily , eudicots , extant taxon , paleontology , evolutionary biology , taxonomy (biology) , fabaceae , biochemistry , gene
Six examples of a spicate inflorescence from the Middle Eocene Claiborne Formation in western Tennessee have been investigated. Individual flowers are small, alternately arranged, nearly sessile, and perfect. The style protrudes 2 mm beyond the floral envelope and terminates in a slightly swollen, rounded stigma. Both the style and the stigma are hairy. Ten stamens are exserted and extend 5 mm beyond the floral envelope. Anthers are small, versatile, and dehisce longitudinally. Pollen grains are tricolporate, tectate, and are in permanent tetrahedral tetrads 32 μ m in diameter. Comparison of the fossil inflorescences with those of extant families having multiple pollen grain configurations suggests that the fossil inflorescences are most closely allied to the subfamily Mimosoideae of the Leguminosae. These are the first structurally documented remains of the Mimosoideae from the Middle Eocene.