The Primary Body of Rellimia thomsonii: Integrated Perspective Based on Organically Connected Specimens

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The University of Chicago Press is collaborating with JSTOR to digitize, preserve and extend access to International Journal of Plant Sciences.The Blenheim-Gilboa locality in New York contains Rellimia thomsonii specimens preserved as both compressions and permineralizations that offer an unusually complete perspective on the reproductive structures, primary body, and secondary anatomy of this Middle Devonian plant. Here we describe the vegetative appendages, axis and branch size relationships, and trace departure as well as primary anatomy, including phloem sieve cells of interconnected axis orders of vegetative and fertile specimens. At least five orders are present, and each axis order is approximately half the diameter of the parent axis. Three-ribbed protosteles are evident in all axes. Protoxylem in transverse section is a continuous three-ribbed sheet one or two tracheids wide, enveloped by several cell layers of metaxylem in turn surrounded by primary phloem. Sieve cells have vertically arranged sieve areas. Trace departure to axes is similar in vegetative and fertile axes. Traces are apparent proximally as radial elongations of the tip of the parent primary xylem rib. In distal sections, the rib tip is tangentially elongated; ultimately, the trace becomes three-ribbed. Traces to vegetative appendages and fertile organs divide dichotomously. The new features described here allow us to expand and complement previous work and to discuss our whole-plant concept of Rellimia.

Buried deep beyond the veil of extinction: Euphyllophyte relationships at the base of the spermatophyte clade

“…Only one of the discrete anatomical‐morphological characters (Appendix 4) is not vegetative, because reproductive structures are known in very few of the taxa included in this study: Psilophyton , Rellimia , Tetraxylopteris , Aneurophyton , and Elkinsia (Beck, ; Banks et al., ; Scheckler, ; Bonamo, ; Serlin and Banks, ; Schweitzer and Matten, ; Rothwell et al., ; Serbet and Rothwell, ; Dannenhoffer et al., ).…”

The Middle Devonian plant assemblage from Dechra Aït Abdallah (Central Morocco) revisited

“…Schweitzer and Matten (1982) observed paired branches in German specimens of Aneurophyton and Rellimia whereas Dannenhoffer et al (2007) described specimens of Rellimia from New York State producing single branches at nodes, like the Moroccan specimens. The full range of variation in the vegetative body of these two genera obviously requires more investigation (Beck and Wight, 1988).…”

“…Lateral branches are strongly pseudomonopodial and show a higher growth potential. Dichotomizing ultimate appendages occur not only on the ultimate order of branches but also on other axes (Schweitzer and Matten, 1982;Beck and Wight, 1988;Dannenhoffer et al, 2007). The Moroccan specimens possess this latter set of derived characters.…”

Mid-Devonian Archaeopteris Roots Signal Revolutionary Change in Earliest Fossil Forests

“…Aneurophytaleans -By contrast, aneurophytaleans observed at Gilboa, and generally common in Catskill sediments as aerial shoots, produced both secondary xylem and phloem [36] similar to that seen in seed plants. Developmental evidence, however, suggests that secondary tissue production was probably limited [37], and it seems likely that most specimens found so far represent determinate portions of the plants that completed development with sterile or reproductive ultimate units, or a mixture of the two [38]. However it remains uncertain how these plants actually grew.…”