''Psaronius'' was a Marattialean

tree fern The tree ferns are arborescent (tree-like) ferns that grow with a trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae (scaly tre ...

which grew to 10m in height, and is associated with leaves of the organ genus '' Pecopteris'' and other extinct tree ferns. Originally, ''Psaronius'' was a name for the petrified stems, but today the genus is used for the entire tree fern. ''Psaronius'' tree fern fossils are found from the Carboniferous through the Permian. Reconstruction of Psaronius

Etymology

The word Psaronius comes from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

ψαρονιος (''psaronius'', precious stone) the

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

of which is ψαρον (''psaron'', a starling bird.] The stone was used for ornamental purposes in Europe and acquired the name for its resemblance to the speckled pattern of the starling. In Germany, the stone was called staarstein. And in English, it was called either starry-stone or starling stone.

Description

Like many extinct trees, psaronius is known by various individual fossil parts that are not always found together. The main parts include: the root mantle, the stem, the fronds, the coziers (fiddleheads), and leaves with spores. Tubiculites

Root mantle

An unusual feature is that ''Psaronius'' did not have a true trunk, but had a massive root mantle formed by hundreds of rootlets. These rootlets are referred to as

adventitious Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living pla ...

because they are appearing in an atypical location. These adventitious roots originate in a central stem high in the tree. This central stem becomes smaller lower in the tree so that at the base the mantle is composed entirely of roots. In some specimens, this mantle is over 1.0 m in diameter at the base of the tree. The fossilized wood of this root mantle is simply referred to as ''Psaronius''. The side impressions of these adventitious roots are referred to as ''Tubiculites'' by the French Geologist

François Cyrille Grand'Eury François Cyrille Grand'Eury (9 March 1839, Houdreville – 22 July 1917, Malzéville) was a French geologist, paleontologist and mathematics teacher. He studied at the École Loritz in Nancy and at the École des mines in Saint-Étienne, a ...

in 1877.

An ecosystem in the ''Psaronius'' root mantle

Like modern tree ferns, ''Psaronius'' included other plant species growing in the root mantle. It has been determined through cross-sections of petrified ''Psaronius'', that various vining and epiphytic plants were growing within the tree fern. Some Carboniferous plant species are only known from their fossilized remains within these root mantles. Some of these that have been studied extensively are the epiphyte '' Botryopteris'', the vining climber '' Ankyropteris'' and the small climbing ferns called '' Tubicaulis''.

Fronds and leaves

The leaves most often associated with ''Psaronius'' are those known as '' Pecopteris'', but some species of ''Psaronius'' bore '' Sphenopteris'' foliage. Fossil of the croziers (or fiddleheads) of the fern fronds have been found. They sometimes go by the name ''Spiropteris''. The study of croziers associated with psaronius wood have been used to determine foliage associations. The fronds were often bipinnate and sometimes tripinnate. Other leaf taxon associated with ''Psaronius'' include: ''

Asterotheca ''Asterotheca'' is a genus of seedless, spore-bearing, vascularized ferns dating from the Carboniferous of the Paleozoic to the Triassic of the Mesozoic. Description ''Asterotheca sp.'' is a vascularized, seedless fern that reproduces vi ...

'', '' Acitheca'', '' Remia'' and '' Radstockia''. File:Pecopteris polymorpha.jpg, Pecopteris polymorpha File:Pecopteris arborescens.jpg, Pecopteris arborescens File:Pecopteris villosa.jpg, Pecopteris villosa

Leaf scar

The bases where the leaves attached were thick to carry the weight of fronds that could attain the size of 2 to 3 meters. stem scars. When fronds abscised from Psaronius, they left elliptical scars on the surface of the stem. Fossils of these leaf scars appear in different arrangements which may indicate different species of trees. These scars are known as ''Caulopteris'', ''Megaphyton'', ''Hagiophyton'', and ''Artisophyton'' based on the four main arrangement patterns. File:Psaronius petiole scars.png, Psaronius stem surface petiole base configurations. A. ''Caulopteris'' . B. ''Megaphyton'' . C. ''Hagiophyton'' . D. ''Artisophyton''

Relationship to modern ferns

''Psaronius'' is in included in the fern family Marattiaceae. Living representatives of this family include many large ferns but none are a 'tree form' like ''Psaronius''. Recent molecular studies indicate that this group of ferns have a very old lineage and may be a sister group to the horsetails

Equisetum ''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a " living fossil", the only living genus of the entire subclass ...

. Modern tree ferns have many similarities to ''Psaronius'' but are in a younger fern family, the Cyatheales.

References

External links

* http://www.xs4all.nl/~steurh/engpsar/epsaron.html * http://botany.cz/en/psaronius/ * http://www.georgesbasement.com/LesquereuxAtlasP/Stemmatopteris-to-Psaronius-Lesquereux.htm {{Taxonbar, from=Q7254004 Marattiidae Pennsylvanian plants