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Early Cretaceous (Early to Middle Albian) Platanoid Inflorescences Associated with Sapindopsis Leaves from the Potomac Group of Eastern North America

Peter R. Crane, Kaj Raunsgaard Pedersen, Else Marie Friis and Andrew N. Drinnan
Systematic Botany
Vol. 18, No. 2 (Apr. - Jun., 1993), pp. 328-344
DOI: 10.2307/2419407
Stable URL: http://www.jstor.org/stable/2419407
Page Count: 17
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Early Cretaceous (Early to Middle Albian) Platanoid Inflorescences Associated with Sapindopsis Leaves from the Potomac Group of Eastern North America
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Abstract

The earliest fossil platanoid reproductive structures so far recorded are from the "bank near Brooke" locality in the Patapsco Formation (Potomac Group) of northern Virginia. Pistillate inflorescences and infructescences (Platanocarpus brookensis, sp. nov.) consist of flowers in globose aggregations that are borne directly on the inflorescence axis. Individual flowers are sessile and each consists of five free carpels, surrounded by a prominent perianth. Staminate inflorescences (Aquia brookensis, gen. et sp. nov.) consist of globose aggregations of flowers containing stamens with long filaments, and anthers with valvate dehiscence and a massive connective. Anthers contain tricolpate foveo-reticulate pollen. Association evidence, similarities in cuticular structure, and the occurrence of Aquia-type pollen on carpels of Platanocarpus brookensis, suggest that these reproductive structures and the co-occurring Sapindopsis leaves were produced by the same plant species. The "Aquia plant" provides further evidence that Sapindopsis leaves are part of the mid-Cretaceous platanoid complex, documents that not all platanoid stamens are characterized by a prominent apical expansion of the connective, and demonstrates for the first time that the pollen produced by the platanoid complex was more diverse than the distinctive reticulate grains previously reported in situ from other Cretaceous and Tertiary platanoid flowers. Based on outgroup comparison and stratigraphic position, many of the features exhibited by the "Aquia plant" may be plesiomorphic for the platanoid clade as a whole.

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