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Steven R Manchester

A new species of poplar is recognized based on abundant specimens from the early Middle Eocene Parachute Creek Member of the Green River Formation in eastern Utah and western Colorado and compared with two other contemporary species. A rare twig bearing both leaves and fruits serves as a Rosetta stone, linking the vegetative and reproductive structures that formerly were only known from dispersed organs. Fruit and foliage characters distinguish Populus tidwellii sp. n. from Populus cinnamomoides (Lesquereux) MacGinitie (typified on specimens from Green River Station, WY), to which the isolated leaves had formerly been attributed. In addition, new data from fruits and foliage confirm that there were two distinct...
A new genus is described based on fossilized winged fruits from former lake deposits of Wyoming, Utah, Colorado, Oregon, and British Columbia, ranging in age from latest Paleocene to early Middle Eocene. Lagokarpos lacustris McMurran et Manchester gen. et sp. nov. fruits have an elliptical to globose seed body and a conspicuous pair of apical wings with pinnate venation. These windâ€ï¿½dispersed fruits are compared with and distinguished from similar extant winged fruits such as Dipterocarpus Gaertn f. (Dipterocarpaceae), Gyrocarpus Jacq. (Hernandiaceae), and Alberta E. Meyer (Rubiaceae). No modern fruit was found to exhibit the combination of characters seen in Lagokarpos, and we conclude that it represents an extinct...
An extinct genus of the Polemoniaceae is described from one complete fossil plant preserved in shale of the Eocene Green River Formation, Utah. Combined vegetative and reproductive characters including the taproot, basal and cauline pinnatifid leaves, primary peduncular leaves, secondary peduncular bracts, pedicel bracts, fruits in groups of three, and persistent calyx, support placement of this plant close to the extant genus Gilia. Gilisenium hueberi gen. et sp. nov. represents a rare record of an herbaceous plant, and the oldest megafossil for the family Polemoniaceae. Published in Review of Palaeobotany and Palynology, volume 104, issue 1, on pages 39 - 49, in 1998.
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