You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. 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.
Carex graceii sp. n., Cyperocarpus eliasii sp. n., Cyperocarpus terrestris sp. n., and Cyperocarpus pulcherrima sp. n. (Cyperaceae) From the Miocene of Nebraska
Joseph R. Thomasson
American Journal of Botany
Vol. 70, No. 3 (Mar., 1983), pp. 435-449
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2443251
Page Count: 15
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.
Preview not available
Silicified achenes and some perigynia of four new sedges are described from the late middle or late Miocene Ash Hollow (Clarendonian or Hemphillian) and early middle Miocene Sheep Creek (Late Hemingfordian) Formations of Nebraska. Carex graceii, sp. n., Cyperocarpus terrestris, sp. n., and Cyperocarpus pulcherrima, sp. n., were collected from strata in Garden and Antelope Counties and Cyperocarpus eliasii, sp. n., was collected from strata in Sioux County. Certain of the newly discovered taxa exhibit considerable anatomical detail of the pericarp wall of the achene. In two taxa, Carex graceii and Cyperocarpus pulcherrima, the achene pericarp exhibits four topographic regions: a cuticle, an outer layer of pentagonally to hexagonally shaped epidermal cells containing silica bodies, a middle layer of sclerenchyma cells, and an inner layer of sclerenchyma cells whose long axes are perpendicular to the long axes of the cells of the middle layer. Similar pericarp anatomy was found in Cyperocarpus terrestris except that the inner layer was not observed. In the fourth taxon, Cyperocarpus eliasii, only an outer epidermal layer of elongate cells with small protuberances is preserved. The ultrastructure of the pericarp of the fossil taxa is similar to that of living forms. Associated flora and fauna indicate widespread savanna environments with significant riparian elements. This is the first systematic treatment of sedges from the Miocene of North America.
American Journal of Botany © 1983 Botanical Society of America, Inc.