Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 28 September 1984:
Vol. 225. no. 4669, pp. 1469 - 1471
DOI: 10.1126/science.225.4669.1469
Prev | Table of Contents | Next

Articles

Sieve Cells in Phloem of a Middle Devonian Progymnosperm

DAVID C. WIGHT 1 and CHARLES B. BECK 1

1 Division of Biological Sciences and Museum of Paleontology, University of Michigan, Ann Arbor 48109

Phloem tissue from a Middle Devonian member of the Aneurophytales (Progymnospermopsida) is described. This may be the oldest firm evidence of conducting elements of the phloem, extending our knowledge of this tissue back some 35 million years. The discovery indicates a close phylogenetic relation between progymnosperms and gymnosperms and provides a basis for investigating patterns of specialization in the phloem of these groups of plants.

Submitted on May 16, 1984
Accepted on July 18, 1984


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Evidence of polar auxin flow in 375 million-year-old fossil wood.
G. W. Rothwell and S. Lev-Yadun (2005)
Am. J. Botany 92, 903-906
   Abstract »    Full Text »    PDF »
Evidence for Queer Genes: An Interview with Richard Pillard.
E. Stein (1993)
GLQ: A Journal of Lesbian and Gay Studies 1, 93-110
   PDF »
A Genetic Study of Male Sexual Orientation.
J. M. Bailey and R. C. Pillard (1991)
Arch Gen Psychiatry 48, 1089-1096
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)