Horneophyton
Graphical reconstruction
Horneophyton lignieri is a fossil species, which was described in 1920 from the Rhynie chert in the Scottish county of Aberdeenshire for the first time. You alone forms the genus Horneophyton. It has no real vessels. Your sporangia are branched.
- 5.1 Notes and references
Features
Sporophyte
The rhizome is relatively large, lobulated to nodular and parenchymatous. It bears numerous unicellular rhizoids.
The axes are high to 20 inches and branch dichotomously ( dichotomous ). They are not in a plane ( planar). They form small multicellular outgrowths. The axis is a protostele. The water-conducting elements have no clear enlargements that would identify them clearly as tracheids. The conducting cells in the center are narrower than the outer. To this central strand is a ring of thin-walled cells, further outside a cortical zone. The epidermis consists of elongated cells and has a well-developed cuticle. The stomata are at the top of the small growths on both the axis as the sporangia.
The sporangia are terminal ( terminal) on the axles. They are cylindrical, hardly distinguishable from the axis. They possess inside a central sterile axis ( columella ). The sporangia branch out two or three times nonplanar, the sporogenous tissue is continuous. The sporangia opened probably with an apical slit. The microspores are 39-71 microns in size, trilet ( with dreistrahliger scar ), rounded and apiculat.
Gametophyte
Langiophyton mackiei was identified as a likely female gametophyte of Horneophyton. He probably grew up aboveground autotrophic. The axis ends in a shield-shaped structure of 10 millimeters in diameter, sitting at roughly 30 short, archegonia -bearing axes. The archegonia have a sunken egg chamber and a massive Archegonienhals. The connection to Horneophyton based on structures of the same routing cells, the epidermal cells and stomata. The vascular tissue branches in the apical plate, there being one vascular bundle pulls in a archegonia -bearing axis.
Ecology
Horneophyton grew on sandy soils that were rich in organic material. Frequently they grew individually, usually on moist to wet sites.
Systematic position
Horneophyton was provided by Harlan P. Banks to Rhyniophyten. Cladistic studies have shown, however, that they are not therefore not part due to the lack of clear tracheids to the vascular plants and the Rhyniophyten. Paul Kenrick and Peter R. Crane have the genus therefore together with Caia and Tortilicaulis which also have branched sporangia, placed in a separate group Horneophytopsida. This group is the sister group of the clade ( Aglaophyton vascular plants ).
Botanical history
Horneophyton was described in 1920 by Robert Kidston and WH Lang in their publication series of the fossils from the Rhynie Chert as Hornea, but had to be renamed in 1938 by Barghoorn and Darrah, since Hornea was already taken. In 1991, the female gametophyte of Remy and hatred has been described.
Documents
- Paul Kenrick, Peter R. Crane: The Origin and Early Diversification of Land Plants. A Cladistic Study. Smithsonian Institution Press, Washington, D.C. 1997, pp. 319F. ISBN 1-56098-729-4
- Thomas N. Taylor, Edith L. Taylor: The Biology and Evolution of Fossil Plants. Prentice Hall, Englewood Cliffs 1993, pp. 199f. ISBN 0-13-651589-4