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PALAEOBOTANICAL RESEARCH   GROUP   UNIVERSITY  MÜNSTER

Sphenophytes or Articulates are a group of spore plants with articulated axes and leaves standing in whorls. Fructifications typically consist of strobili. Sphenophytes were widespread in the Carboniferous and Early Permian. Two major groups can be distinguished, the Calamitales and the Sphenophyllales. The calamites were rhizome-borne trees with secondary growth which could reach a height of up to 20 m. Most species are indicative for humid to wet environments. They often occurred in monotypic stands along the shorelines of lakes and rivers, probably comparable to modern reed vegetations. The name Calamites was originally given to pith casts of the hollow stems, but is now also used for the whole plant. Annularia and Asterophyllites are two types of calamite foliage. The sphenophylls were herb-like plants with typical wedge-shaped leaves arranged in whorls. The only living sphenophyte is the modern Equisetum or horsetail.

Taxon / Subject	Web Source	Comments	Pics	Info
Calamites is a genus for the stems of fossil giant horsetails.  The genus has been established for the pith casts, the natural infillings of the hollow central parts of the stem.  The stems are articulated and have nodes and internodes.  Calamites shows characteristic ribs which normally alternate at the nodes.  The pithcasts only give an idea about the diameter of the internal cavity of the stem, not about the diameter of the stem itself !  Outer stem surfaces are rare. The generic name is also used for permineralized stems, e.g. in coal balls. Many species have been described.  However, the taxonomy is rather confusing.
Calamites carinatus	Plant fossils from the Northen Anthracite Field
Calamites cistii	Plant fossils from the Northen Anthracite Field
Calamites cistii	M. Hieb's Plant Fossils of West Virginia
Calamites cistii	M. Hieb's Plant Fossils of West Virginia
Calamites cistii	M. Hieb's Plant Fossils of West Virginia	branching axes
Calamites	M. Hieb's Plant Fossils of West Virginia	outer surface with branch scars
Calamites sp.	Mazon Creek Exhibit, Illinois State Museum
Calamites sp.	Kansas Fossils, Geology Museum, Emporia State University
Calamites	Collection Jens-Wilhelm Janzen
Calamites	Kathleen Pigg's "Plant Fossils and Evolution"
C alamites	R.A. Spicer, The Open University, Milton Keynes
Calamites	Manny's Fossil Gallery
Calamites	Manny's Fossil Gallery
Calamites	Botanical Society of America: Online Image Collection	coal ball: longitudinal section
Calamites	Botanical Society of America: Online Image Collection	as above; high resolution image
Calamites	Botanical Society of America: Online Image Collection	coal ball: cross section
Calamites	Botanical Society of America: Online Image Collection	as above; high resolution image
Calamites	Botanical Society of America: Online Image Collection	coal ball: cross section
Calamites	Botanical Society of America: Online Image Collection	as above; high resolution image
Calamites	Botanical Society of America: Online Image Collection	coal ball: cross section
Calamites	Botanical Society of America: Online Image Collection	as above; high resolution image
Annularia is a genus for calamitalean foliage. The narrow lancet-like Annularia leaves are placed in whorls, positioned at the nodes. All leaves lie in one plane and the whorls are circular to oval in outline.  Several dozens of species are distinguished, some of them being valuable index fossils.
Annularia radiata	M. Hieb's Plant Fossils of West Virginia
Annularia radiata	M. Hieb's Plant Fossils of West Virginia
Annularia mucronata	Plant fossils from the Northen Anthracite Field
Annularia stellata	Plant fossils from the Northen Anthracite Field
Annularia sp.	Mazon Creek Exhibit, Illinois State Museum
Annularia sp.	Kansas Fossils, Geology Museum, Emporia State University
Annularia	Collection Jens-Wilhelm Janzen
Annularia sphenophylloides	Kathleen Pigg's "Plant Fossils and Evolution"
Asterophyllites is another type of calamitalean foliage. The narrow needle-shaped leaves are also positioned in whorl inserted at the nodes but all leaves are directed towards the apex of the shoot.  The leaf whorls are laterally compressed. Some of the Asterophyllites species are valuable index fossils.
Asterophyllites equisetiformis	Mazon Creek Exhibit, Illinois State Museum
Asterophyllites charaeformis	M. Hieb's Plant Fossils of West Virginia
Asterophyllites equisiteformis	M. Hieb's Plant Fossils of West Virginia
Asterophyllites equisetiformis	Natural History Museum, Maastricht, The Netherlands
Asterophyllites equisetiformis	Kathleen Pigg's "Plant Fossils and Evolution"
Asterophyllites	Collection Jens-Wilhelm Janzen
Asterophyllites	Botanical Society of America: Online Image Collection	coal ball material
Asterophyllites	Botanical Society of America: Online Image Collection	coal ball material
Calamostachys is a genus that has been defined for one of the fructification types of Calamitaleans.  The stobilus axes are articulated like all the other axial parts of the plant and bear bracts at the nodes.  The sporophylls holding the sporangia are inserted in between on the internodes.  The exact mode of attachment of the sporophylls is often difficult to recognise in compression material.
Calamostachys sp.	M. Hieb's Plant Fossils of West Virginia
Calamostachys	M. Hieb's Plant Fossils of West Virginia
Calamostachys	Collection Jens-Wilhelm Janzen
Calamostachy binneyana	Botanical Society of America: Online Image Collection	coal ball: cross section
Calamostachys binneyana	Botanical Society of America: Online Image Collection	as above; high resolution image
Calamostachy binneyana	Botanical Society of America: Online Image Collection	coal ball: longitudinal section
Calamostachs binneyana	Botanical Society of America: Online Image Collection	as above; high resolution image
Sphenophyllum is a genus of spore plants with articulated axes and wedge-shaped leaves which are positioned in whorls, inserted at the nodes.  Leaf whorls usually hold six leaves.  The genus Sphenophyllum was originally established for leaf compressions but is now also used for permineralised axes.  In crsoss section the axes show a typical triarch xylem with secondary growth.  Sphenophylls were herbaceous plants, at least several species had a scrambling growth habit.  The various Sphenophyllum foliage species are valuable index fossils for the Upper Carboniferous and Lower Permian.
Sphenophyllum cuneifolium	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum cuneifolium	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum emarginatum	Plant fossils from the Northen Anthracite Field
Sphenophyllum emarginatum	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum	M. Hieb's Plant Fossils of West Virginia
Sphenophyllum	Collection Jens-Wilhelm Janzen
Sphenophyllum	Kathleen Pigg's "Plant Fossils and Evolution"	coal ball material: cross section
Sphenophyllum plurifoliatum	Botanical Society of America: Online Image Collection	coal ball material: cross section
Sphenophyllum plurifoliatum	Botanical Society of America: Online Image Collection	as above; high resolution image
Sphenophyllum	Botanical Society of America: Online Image Collection	coal ball material: cross section
Sphenophyllum	Botanical Society of America: Online Image Collection	as above; high resolution image
Only a single genus of sphenophytes has survived up the present day, Equisetum.  All species are herbaceous. The following site gives some information on extant sphenophytes.
Modern sphenophytes	University of California Museum of Paleontology, Berkeley

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