Rhynie II

PALAEOBOTANICAL RESEARCH GROUP

UNIVERSITY MÜNSTER

THE RHYNIE CHERT AND ITS FLORA

II. THE RHYNIE CHERT FLORA

	In addition to vascular plants, many fungi, algae and even the earliest well-documented lichens have been described from the Rhynie Chert. The latter is a typical example of a symbiosis of a fungus and algae or cyanobacteria. Also other examples of interactions between fungi, land plants and animals, e.g., parasitism and saprophytism have been documented from the Rhynie Chert. Six different types of sporophytes and three gametophytes have been described. Because the recent drillings have cored several previously unknown chert horizons, it might well be possible that new plant species can be found; from the nearby Windyfield Chert a new genus of zosterophylls has been reported recently. Many of the plants in the cherts occur in life position.
	Left: A piece of Rhynie Chert with several horizons, including upright standing Aglaophyton major axes (above)
The following plants have been reported from the Rhynie Chert:

Cyanobacteria:

Archaeothrix contexta
Archaeothrix oscillatoriformis
Kidstoniella fritschii
Langiella scourfeldii
Rhyniella vermiformis
Rhyniococcus uniformis

Fungi:

Allomyces sp.
Glomites rhyniensis
Krispiromyces discoides
Milleromyces rhyniensis
Palaeoblastocladia milleri
Palaeomyces agglomerata
Palaeomyces asteroxyli
Palaeomyces gordonii
Palaeomyces horneae
Palaeomyces simpsonii
Palaeomyces simpsonii
Several Chytridiomycetes
Ascomycetes
Various other undescribed fungi

Lichens:

Winfrenatia reticulata

Nematophytes:

Nematophyton taitii
Nematoplexus rhyniensis

Algae s.l.:

Mackiella rotundata
Palaeonitella cranii
Rhynchertia punctata

Tracheophytes (Sporophytes):

Aglaophyton major
Asteroxylon mackiei
Horneophyton lignieri
Nothia aphylla
Rhynia gwynne-vaughanii
Trichopherophyton teuchansii
Ventarura lyonii

Tracheophytes (Gametophytes):

Langiophyton mackiei
Lyonophyton rhyniensis
Kidstonophyton discoides
Still undescribed female gametophyte of Aglaophyton major
Still undescribed female and male gametophytes of Rhynia gwynne-vaughanii
Still undescribed male gametophyte of Horneophyton lignieri

List of plants described from the Rhynie Chert

The vascular land plants were small, ca. 10 to 40 cm high. Except for one species, all higher land plants were leafless and all had bifurcating aerial axes with terminally and/or laterally attached sporangia with thick multilayered walls. All species had clonal growth which means that aerial axes (daughter plants) developed from the rhizomatic axes of the mother plant. Each species had its characteristic growth form, which indicates that each was well adapted to a specific habititat. Some species had long-living aerial axes whereas others had seasonal aerial axes. Two species lived entirely subaerial (Rhynia gwynne-vaughanii und Aglaophyton major), two had a subterranean rhizome (Nothia aphylla, Horneophyton lignieri), whereas ones species had roots which penetrated the soil (Asteroxylon mackiei). Adaptations of these early land plants to the substrate and the available groundwater were apparently still limited. Each species has water-conducting cells with very typical wall thickenings that are very different from those of later vascular plants.

The systematic position of a number of species is problematic, not because they are not well known but rather because suprageneric groups are poorly defined. There is still much discussion on the classification of some of the Rhynie Chert plants. At least two of the six natural species are classified within the group of the Rhyniophytes, one within the Zosterophyllophytes and one among the earliest lycopods. Some of the Rhynie Chert plants will be briefly introduced on the following pages.

Left: Reconstruction of Aglaophyton major, one of the most common plants in the Rhynie Chert

December 2002