Home / Introductions to both Fossil and Recent Plant Taxa / Sphenophyta

C. Álvarez-Vázquez and R.H. Wagner (2017): A revision of Annularia and Asterophyllites species from the lower Westphalian (Middle Pennsylvanian) of the Maritime Provinces of Canada. Abstract, Atlantic Geology, 53: 17-62. See also here (in PDF).

! H. Anderson and J. Anderson (2018): Molteno Sphenophytes: Late Triassic Biodiversity in Southern Africa. Palaeont. afr., 53 (Special Issue): i–ix + 1–391. See also here. In PDF (slow download, 183 MB!).
Available through the Internet Archive´s Wayback Machine.

P. Appleton et al. (2011): The Brymbo Fossil Forest. In PDF, Geology Today, 27: 107–113.
See also here.

! Nan Crystal Arens, C. Strömberg and A. Thompson, Department of Integrative Biology, and Paleobotany Section, Museum of Paleontology (UCMP), University of California at Berkeley: Virtual Paleobotany. The Virtual Paleobotanical Laboratory, a comprehensive treatment of the fossil record of land plants, is divided into 12 chapters, lab I through XII. Each lab has a title page, a page with questions around the group or subject of study, a list of literature and links for further reading and exploration, and a virtual gallery of images from the lab. Go to: Sphenopsids and Ferns.

! J. Armstrong and W. Armstrong (2009): Record rates of pressurized gas-flow in the great horsetail, Equisetum telmateia. Were Carboniferous Calamites similarly aerated? Free access, New Phytologist, 184: 202–215. Also worth to check out:
J.A. Raven (2009): Horsetails get the wind up. In PDF, New Phytologist, 84: 6–9.

! Lorna Ash & Heather Kroening, Department of Biological Sciences, University of Alberta: Instructional Multimedia, Multimedia Topics, Botany. Go to: Equisetum life cycle, Fern Life Cycle. See also here. Online and downloadable flash 4 movies. Excellent!

A.T. Aung et al. (2020): Three new fossil records of Equisetum (Equisetaceae) from the Neogene of south-western China and northern Vietnam. Open access, PhytoKeys, 138: 3–15.

Centre for Plant Biodiversity Research, Australian National Herbarium, Canberra:
Fern Pages.
Pteridophytes: The Ferns and their Allies.
Websites outdated. Links lead to versions archived by the Internet Archive´s Wayback Machine.

M. Barbacka (2009): Sphenophyta from the Early Jurassic of the Mecsek Mts., Hungary. Snapshot taken by the Internet Archive´s Wayback Machine. PDF file, Acta Palaeobotanica 49: 221-231. Cuticle showing stomata of Equisetites columnaris in fig. 15!

C. Barbosa et al. (2022): Phyllotheca douroensis sp. nov., a new equisetalean fossil-species from the Douro Carboniferous Basin (Upper Pennsylvanian; NW Portugal): palaeobiogeographical, systematic and evolutionary implications. Free access, Biosis: Biological Systems, 3:e001. https://doi.org/10.37819/biosis.003.01.0162.
See also here.
Note fig. 4: Phyllotheca (Raniganjia?) etheridgei Arber 1905.

Bayerische Staatssammlung für Paläontologie und Geologie, München: Fossil des Monats (in German). Go to Blattscheide eines Schachtelhalmgewächses. Leaf sheath impression of Equisetites arenaceus.
Websites outdated. Links to versions archived by the Internet Archive´s Wayback Machine.

W. Bennert et al. (2005): Triploidy in Equisetum subgenus Hippochaete (Equisetaceae, Pteridophyta). PDF file, Annals of Botany, 95: 807-815.

Museum of Paleontology (UCMP), University of California at Berkeley: Introduction to the Sphenophyta.

B. Bomfleur et al. (2013): A reappraisal of Neocalamites and Schizoneura (fossil Equisetales) based on material from the Triassic of East Antarctica. See also here (abstract).

! The Botanical Society of America: The American Journal of Botany Cover Images Index. The collection on the page holding the cover images of the American Journal of Botany. A great set of images! See also:
! Online Image Collection. This page acts as a map to the entire collection. Images are classified in groups in which they were submitted for historical purposes, e.g. Paleobotany.
See especially: Sphenophyta.
Snapshots taken by the Internet Archive´s Wayback Machine.

M. Brea and A.A. Artabe (1999): Apocalamitaceae (Sphenophyta) triásicas de la Formación Paramillo, Agua de la Zorra, provincia de Mendoza Argentina. In Spanish, Ameghiniana, 36 (Google books).

The British Pteridiological Society. The British Pteridological Society provides a wide range of information about ferns for fern enthusiasts. It also organises formal talks, informal discussions, field meetings, garden visits, plant exchanges, a spore exchange scheme and fern book sales. Go to: An Introduction to Ferns. Snapshot taken by the Internet Archive´s Wayback Machine. This introduction (to ferns and other pteridophytes) is based on a chapter from the book "A World of Ferns", by Josephine M. Camus, A. Clive Jermy & Barry A. Thomas, Natural History Museum Publications, London.

! H. Brunner and K.-P. Kelber (1988): Eisenerzkonkretionen im württembergisch-fränkischen Unterkeuper - Bemerkungen zum fossilen Environment. PDF file, in German. In: Hagdorn, H. (ed.): Neue Forschungen zur Erdgeschichte von Crailsheim. Sonderbände d. Ges. f. Naturk. in Württemberg, 1: 185-205.
Anatomical views of the Triassic horsetail Neocalamites merianii in pyrite/goethite preservation.

Benjamin Burger, Utah State University, Vernal, Utah:
Why study fossil plants?
Invertebrate Paleontology and Paleobotany.
How did plants colonize the land, based on the fossil record?
How did the first seed plants (the Gymnosperms) evolve?
How did gymnosperms diversify during the early Mesozoic to become a modern dominate plant group?
How good is the fossil record of Cycads?
What is the significance of the fossil record of Ginkgo?
! What is the fossil record of Horsetails?
Fossil Algae.
What is an Angiosperm?
Video lectures.

Reiner Burger, Frankfurter Allgemeine Zeitung: Holzversteinerungen. Unter dem Pflaster der Wald. Ramified Calamites axes from Chemnitz (in German).
Snapshot taken by the Internet Archive´s Wayback Machine.

! A. Channing et al. (2011): Equisetum thermale sp. nov.(Equisetales) from the Jurassic San Agustín hot spring deposit, Patagonia: Anatomy, paleoecology, and inferred paleoecophysiology. PDF file, American Journal of Botany, 98: 680-697.
A version archived by Internet Archive Wayback Machine.
See also here (abstract).

H.Y. Chen et al. (2020): The Oligocene Equisetum from Qaidam Basin, Northeastern Tibetan Plateau in China and its implications. In PDF, Historical Biology, DOI: 10.1080/08912963.2020.1830280.

! M.J.M. Christenhusz et al. (2021): Biogeography and genome size evolution of the oldest extant vascular plant genus, Equisetum (Equisetaceae). Free access, Annals of Botany, 127: 681–695.
Note figure 2: Tree of Equisetum.
Figure 3: Spatiotemporal evolution of Equisetum.
"... With a calculated age of 342 Mya, we place the origin of the ancestor of the extant members of Equisetaceae in the Early Carboniferous, with Equisetum evolving at some point after that, probably soon, but definitely before 175 Mya, making it possibly the oldest extant genus of vascular plants. ..."

! M.J.M. Christenhusz et al. (2019): Phylogenetics, classification and typification of extant horsetails (Equisetum, Equisetaceae). Abstract, Botanical Journal of the Linnean Society, 189: 311–352. See also here (in PDF).

! Curtis Clark, Biological Sciences Department California State Polytechnic University, Pomona: Plant Morphology. Resources, PDF files.
Website outdated. The link is to a version archived by the Internet Archive´s Wayback Machine.

J.W. Clark et al. (2019): Origin of horsetails and the role of whole-genome duplication in plant macroevolution. In PDF, Proc. R. Soc., B, 286: 20191662. See also here.

! Michael Clayton, Department of Botany, University of Wisconsin, Madison: Instructional Technology (BotIT). Some image collections. Excellent! Go to:
Fern Allies. See also: Equisetales.

P. Correia et al. (2021): The equisetalean Iberisetum wegeneri gen. nov., sp. nov. from the Upper Pennsylvanian of Portugal. In PDF, Historical Biology. See also here.

! P. Correia et al. (2020): The History of Herbivory on Sphenophytes: A New Calamitalean with an Insect Gall from the Upper Pennsylvanian of Portugal and a Review of Arthropod Herbivory on an Ancient Lineage. In PDF, Int. J. Plant Sci., 181. See also here.
Please take notice of fig. 3: Interpretative-view drawing of Annularia paisii sp. nov. and Paleogallus carpannularites ichnosp. nov.
Fig. 4: Reconstruction of the parasitic relationship between the insect-induced gall Paleogallus carpannularites ichnosp. nov. and its calamitalean host plant.

E.P. Coturel et al. (2016): Lycopodiopsids and equisetopsids from the Triassic of Quebrada de los Fósiles Formation, San Rafael Basin, Argentina. In PDF, Geobios. See also here (abstract).

A. Crisafulli and A. Lutz (2008): Un nuevo tallo permineralizado de Equisetales de la Formación Los Rastros (Triásico Medio - Superior), provincia de San Juan, Argentina.
A new permineralized Equisetalean stem from Los Rastros Formation (Middle-Upper Triassic) from San Juan province, Argentina. . In PDF, Revista del Museo Argentino de Ciencias, 10: 71-79.

! E. Cullen and P.J. Rudall (2016): The remarkable stomata of horsetails (Equisetum): patterning, ultrastructure and development. Abstract, Annals of Botany, 118: 207–218.
See also here (in PDF).

D.L. Des Marais et al. (2003): Phylogenetic Relationships and Evolution of Extant Horsetails, Equisetum, Based on Chloroplast DNA Sequence Data (rbcL and trnL-F). In PDF, Int. J. Plant Sci. 164: 737-751.
See also here.

L.V. de Soane (2005): Equisetites pusillus sp. nov. from the Aptian of Patagonia, Argentina. PDF file, Revista del Museo Argentino de Ciencias.
Now provided by the Internet Archive´s Wayback Machine.

W.A. DiMichele et al. (2009): Catastrophically buried Middle Pennsylvanian Sigillaria and calamitean sphenopsids from Indiana, USA: What kind of vegetation was this? PDF file, Palaios, 24: 159-166.
Now recovered from the Internet Archive´s Wayback Machine.
Reconstruction of a Sigillaria vegetation during early stages of flooding and burial in fig. 6.

W.A. DiMichele et al. (2005): Equisetites from the Early Permian of North-Central Texas. PDF file. In: Lucas, S.G. and Zeigler, K.E., (eds.), The Nonmarine Permian, New Mexico Museum of Natural Histojy and Science Bulletin, 30.
See also here.

! A.B. Doweld (2013): Proposals to conserve the names Equisetites against Oncylogonatum with a conserved type and Equisetum columnare (Equisetites columnare) against Oncylogonatum carbonarium with a conserved type (fossil Equisetopsida). In PDF, Taxon, 62: 837-839.

! A. Elgorriaga et al. (2018): Origin of Equisetum: Evolution of horsetails (Equisetales) within the major euphyllophyte clade Sphenopsida. Abstract, American Journal of Botany, 105.
"We recovered Equisetaceae + Neocalamites as sister to Calamitaceae + a clade of Angaran and Gondwanan horsetails, with the four groups forming a clade that is sister to Archaeocalamitaceae. The estimated age for the Equisetum crown group is mid-Mesozoic". "Modern horsetails are not nested within calamitaceans; instead, both groups have explored independent evolutionary trajectories since the Carboniferous".

! A. Elgorriaga et al. (2015): Reconstruction and Phylogenetic Significance of a New Equisetum Linnaeus Species from the Lower Jurassic of Cerro Bayo (Chubut Province, Argentina). In PDF, Ameghiniana, 52. Nodal reconstruction of Equisetum dimorphum on page 146!

! Z. Feng et al. (2012): When horsetails became giants. Free access, Chinese Science Bulletin, 57: pages 2285–2288.
Reconstruction of the horsetail tree Arthropitys bistriata.

J. Georg Friebe: Schachtelhalme (Equisetaceae) aus der Kössen-Formation (Rhaetium) der Nördlichen Kalkalpen Vorarlbergs. PDF file, Vorarlberger Naturschau, Dornbirn (in German).

! Florida Museum of Natural History, University of Florida, Gainesville:
Sphenopsids (Powerpoint presentatation).

R.A. Gastaldo (1992): Regenerative growth in fossil horsetails following burial by alluvium. In PDF, Historical Biology: An International Journal of Paleobiology, 6: 203-219. See also here
and there.

S.C. Gnaedinger et al. (2023): Triassic Equisetites lateralis Phillips with strobilus in organic connection from Patagonia of Argentina and endophytic oviposition insect scars. Abstract, Review of Palaeobotany and Palynology.

L. Grauvogel-Stamm and S. Ash (1999): "Lycostrobus" chinleana, an equisetalean cone from the Upper Triassic of the southwestern United States and its phylogenetic implications. PDF file, American Journal of Botany, 86: 1391-1405.

Alena Gribskov: Reconstructing Calamites: Building Giants from Fragments. PDF file, Yale College Writing Center, EEB 171: Collections of the Peabody Museum.

G. Guerriero et al. (2018): Rough and tough. How does silicic acid protect horsetail from fungal infection? Journal of Trace Elements in Medicine and Biology, 47: 45-52.
See also here.

T.G. Halle (1913): II.—On upright Equisetites Stems in the Oolitic Sandstone in Yorkshire. Abstract, Geological Magazine, 10: 3-7.

T.M. Harris (1941): XXV.-On some Specimens of Equisetites columnaris Brongn. In PDF, Annals and Magazine of Natural History, 8: 292-298. See also here.

Monte Hieb and Harrison Hieb: Plant Fossils of West Virginia. Fossil Plants of the Middle Pennsylvanian Period. Go to: Articulates (Sphenopsids).
Snapshots taken by the Internet Archive´s Wayback Machine.

Josef Hlasek: Photo Gallery wildlife pictures, Plants. Go to: Plants - Pteridophyta.

W.B.K. Holmes (2001): Equisetalean Plant Remains from the Early to Middle Triassic of New South Wales, Australia. In PDF, Records of the Australian Museum, 53: 9-20.
See also here.

G. Holzhüter et al. (2003): Structure of silica in Equisetum arvense. In PDF, Anal. Bioanal. Chem., 376: 512-517.
Provided by the Internet Archive´s Wayback Machine.

! C. Husby (2013): Biology and Functional Ecology of Equisetum with Emphasis on the Giant Horsetails. Abstract, The Botanical Review.

! C. Husby and R. Walkowiak (2012): An Introduction to the Genus Equisetum (Horsetail) and the Class Equisetopsida (Sphenopsida) as a whole. In PDF, IEA & WEP Botanical Report.

C.E. Husby et al. (2011): Salinity tolerance ecophysiology of Equisetum giganteum in South America: a study of 11 sites providing a natural gradient of salinity stress. Open access, AoB PLANTS.

C.E. Husby (2009): Ecophysiology and Biomechanics of Equisetum giganteum in South America. In PDF, thesis, Florida International University.

! Chad Husby: Horsetails. Beautiful photographs of Equisetum giganteum. Excellent!

! Chad E. Husby, Department of Biological Sciences, Florida International University, Miami: The Giant Horsetails. Worth to check out:
! An Introduction to the Genus Equisetum and the Class Sphenopsida as a whole, and How large are the giant horsetails?.
These expired links are now available through the Internet Archive´s Wayback Machine.

! The Interactive Geology Project (by Paul Weimer et al., Energy and Minerals Applied Research Center, Denver Museum of Nature & Science, University of Colorado.
The goal of this website is producing short 3D animations about the geologic evolution of key US national parks. Go to: ! Video Library. Excellent!
See especially (scroll down): "Triassic Thickets: Placerville, Colorado, 225 Million Years Ago."
This scene shows the plants developed on a broad coastal plain in western Colorado near Placerville. Plants depicted: Neocalamites, Sanmiguelia. This version is part of a joint project between the Interactive Geology Project at the University of Colorado Boulder and the Denver Museum of Nature and Science. See also here.

International Equisetological Association (IEA). Equisetum, Equisetaceae, Plant Biology.
IEA was founded in 2008 and is dedicated to the development of Equisetum biology; the distribution of Equisetum information; and international cooperation among equisetologists and pterydological organizations. Worth checking out:
! The morphology of Equisetum.
! The life cycle of Equisetum.
! Equisetum Taxonomy.

A. Jarzynka and G. Pacyna (2015): Fossil flora of Middle Jurassic Grojec clays (southern Poland). Raciborski´s original material reinvestigated and supplemented. I. Sphenophytes. In PDF, Acta Palaeobotanica, 55. See also here.

! W. Jongmans (1922): Fossilium Catalogus ll. Plantae. Pars 9: Equisetales. In PDF.

K.-P. Kelber (2015): 5. Die Makroflora des Lettenkeupers . PDF file, in German; p. 51-100, in: Hagdorn, H., Schoch, R. & Schweigert, G. (eds.): Der Lettenkeuper - Ein Fenster in die Zeit vor den Dinosauriern. Palaeodiversity, Special Issue (Staatliches Museum für Naturkunde Stuttgart).
See also here.

K.-P. Kelber and R. Schoch (2015): 18. Lebensbilder des Lettenkeupers im Wandel der Zeiten. PDF file, in German.
p. 407-413; in: Hagdorn, H., Schoch, R. & Schweigert, G. (eds.): Der Lettenkeuper - Ein Fenster in die Zeit vor den Dinosauriern. Palaeodiversity, Special Issue (Staatliches Museum für Naturkunde Stuttgart).
! You may also navigate via back issues of Palaeodiversity 2015. Then scroll down to: Table of Contents "Special Issue: Der Lettenkeuper - Ein Fenster in die Zeit vor den Dinosauriern".
Still available via Internet Archive Wayback Machine.

! K.-P. Kelber (2009): Lebensbilder der Unterkeuperzeit im Spiegel der paläontologischen Forschung. PDF file (8.5 MB), in German. Veröffentlichungen Naturhistorisches Museum Schleusingen, 24: 27-52.
Life pictures from the Lower Keuper in the mirror of palaeontological research. A selection of Lower Keuper swamp reconstructions from the germanotype Triassic (Ladinian, Triassic).

K.-P. Kelber (2005): Makroflora (Die Keuperfloren). PDF file (12 MB), in German. In: Beutler, G., Hauschke, N., Nitsch, E. and Vath, U. (eds.): Deutsche Stratigraphische Kommission, Stratigraphie von Deutschland IV - Keuper. Cour. Forsch.-Inst. Senckenberg, 253: 32-41. Triassic horsetail fossils on plate 1, e.g. Equisetites arenaceus, Neocalamites merianii, Schizoneura paradoxa.

! K.-P. Kelber & J.H.A. van Konijnenburg-van Cittert (1998): Equisetites arenaceus from the Upper Triassic of Germany with evidence for reproductive strategies. Abstract, Rev. Palaeobot. Palynol., 100: 1-26. See also here (in PDF).
Paper awarded with the Winfried and Renate Remy Award 1999 (Paleobotanical Section), Botanical Society of America.

K.-P. Kelber (1992): Der dreidimensionale Bau der Blattspitzen bei Equisetites arenaceus (Equisetopsida, Equisetales) aus dem Unteren Keuper (Trias, Ladin). PDF file, in German. In: Kovar-Eder, J. (ed.): Palaeovegetational development in Europe.- Proc. Pan-European Palaeobot. Conf. Vienna (PEPC 1991), pp. 289-299.

K.-P. Kelber (1983): Schizoneura paradoxa Schimp. & Moug. aus dem Unteren Keuper Frankens. In PDF (32 MB), Naturw.-Jb. Schweinfurt, 1: 19-33.

Kentucky Geological Survey, University of Kentucky, Lexington, KY:
Fossils of the Month. Go to:
! Fossil of the month: Calamites.
Note the illustration: How fossils are formed from pith casts, external, and internal casts and impressions.

H. Khalilizadeh et al. (2022): Two fossilized swamps containing in situ Sphenophyta stems, rhizomes, and root systems from the Middle Jurassic Hojedk Formation, Kerman area (Iran) . In PDF, Palaeobiodiversity and Palaeoenvironments.
See also here.
Note fig. 6: Aerial organs of in situ equisetalean stem.

! A. Knowlton (2012): Quick guide Equisetum. In PDF, Current Biology, 10.

E. Kon'no (1973): New species of Pleuromeia and Neocalamites from the Upper Scythian Bed in the Kitakami Massif, Japan. PDF file, Sci. Rep. Tohoku Univ., 43.
Still available via Internet Archive Wayback Machine.
See also here.

E. Kon´no (1960): Schizoneura manchuriensis Kon´no and its Fructification (Manchurostachys n. gen.) from the Gigantopteris-nicotianaefolia-bearing Formation in Penchihu Coal-field, Northeastern China. In PDF.

S. Kundu et al. (2023): Evidence of the oldest extant vascular plant (horsetails) from the Indian Cenozoic. Free access, Plant Diversity.

M.H. Kurmann and T.N. Taylor (1984): Comparative ultrastructure of the sphenophyte spores Elaterites and Equisetum. Free access, Grana, 23: 109-116.

Kurt Stüber´s Online Library. A collection of historic and modern biology books. Go to: BioLib alphabetic index of Latin plant species names. Latin names used in this index often do not correspond to modern botanical nomenclature. See for instance: Equisetum hyemale.

E. Kustatscher et al. (2007): Horsetails and seedferns from the Anisian locality Kühwiesenkopf (Dolomites, Northern Italy). Free access, Palaeontology, 50: 1277-1298.

E. Kustatscher and J.H.A. van Konijnenburg-van Cittert (2008): Neocalamites asperrimus (Franke) Shen 1990, a morphospecies for Triassic sphenophyte "cortical structures"? Abstract, 18th Plant Taphonomy Meeting, Vienna, Austria.
Snapshot provided by the Internet Archive´s Wayback Machine.

J. Kvacek and A. Cernanský (2023): Early Cretaceous Equisetites from Slovakia. Open access, Palaeobiodiversity and Palaeoenvironments. https://doi.org/10.1007/s12549-023-00596-w.

M. Laaß et al. (2020): First evidence of arthropod herbivory in calamitalean stems from the Pennsylvanian of Germany. In PDF, Annales Societatis Geologorum Poloniae, 90: 219-246. See also here.
Note fig. 7: Taphonomy and fossilization of the calamitalean pith cast with arthropod borings.

O. Leroux et al. (2011): An extensin-rich matrix lines the carinal canals in Equisetum ramosissimum, which may function as water-conducting channels. In PDF, Annals of Botany, 108: 307-319. See also here.

Z. Li et al. (2019): New Discovery of Neocalamites from the Upper Triassic Daheba Formation in West Qinling, Northwest China Acta Geologica Sinica (English Edition), 2019, 93: 756–757.

M. Libertín et al. (2014): New sphenophyllaleans from the Pennsylvanian of the Czech Republic. In PDF, Review of Palaeobotany and Palynology, 200: 196-210.
See also here.

Biological Sciences, Ohio State University, Lima: Plant Biology at OSU Lima.
This expired link is now available through the Internet Archive´s Wayback Machine.

L. Liu et al. (2020): A whole calamitacean plant Palaeostachya guanglongii from the Asselian (Permian) Taiyuan Formation in the Wuda Coalfield, Inner Mongolia, China. Abstract, Review of Palaeobotany and Palynology. See also here (in PDF).
Please note the whole plant reconstruction in figure 18.

L. Luthardt et al. (2016): Palaeoclimatic and site-specific conditions in the early Permian fossil forest of Chemnitz—Sedimentological, geochemical and palaeobotanical evidence. In PDF, Palaeogeography, Palaeoclimatology, Palaeoecology, 441: 627–652.
See also here.

R. Makia et al. (2022): Phytochemistry of the Genus Equisetum (Equisetum arvense). Free access, GSC Biological and Pharmaceutical Sciences, 18: 283–289.
See also here.
"... The current review highlights the uses and phytochemical constituents of E. arvense. ..."

C. Martín-Closas et al. (2018): New palaeobotanical data from Carboniferous Culm deposits constrain the age of the Variscan deformation in the eastern Pyrenees. Abstract, Geologica acta, 16: 107-123. See also here and there (in PDF).

Michael Matus: The Wonderful World of Equisetum.

M. Mazaheri-Johari et al. (2021): A monotypic stand of Neocalamites iranensis n. sp. from the Carnian Pluvial Episode (Late Triassic) of the Aghdarband area, NE Iran (Turan Plate). In PDF, Riv. It. Paleontol. Strat., 127: 189-209.

MDR Sachsen (a TV station), Region Chemnitz: Riesenschachtelhalm ist Fossil des Jahres (video report, in German). See also here (abstract Rößler and Noll (2006), the largest known anatomically preserved Calamites trunk.

! V. Mencl et al. (2013): First anatomical description of silicified calamitalean stems from the upper Carboniferous of the Bohemian Massif (Nová Paka and Rakovník areas, Czech Republic). In PDF, Review of Palaeobotany and Palynology, 197: 70-77. See also here (abstract).

! Palaeobotanical Research Group, Münster, Westfälische Wilhelms University, Münster, Germany. History of Palaeozoic Forests, FOSSIL AND EXTANT SPHENOPHYTES. Link list page with rankings and brief explanations. Images of Calamites, Calamites carinatus, Calamites cistii, Annularia, Annularia radiata, Annularia mucronata, Annularia stellata, Annularia sphenophylloides, Asterophyllites, Asterophyllites equisetiformis, Asterophyllites charaeformis, Asterophyllites longifolius, Calamostachys, Calamostachy binneyana, Sphenophyllum, Sphenophyllum cuneifolium, Sphenophyllum emarginatum, Sphenophyllum longifolium, Sphenophyllum majus, Sphenophyllum geinitzii, Sphenophyllum plurifoliatum.
Website outdated, download a version archived by the Internet Archive´s Wayback Machine.

! S.V. Naugolnykh (2009): A new fertile Neocalamites from the Upper Permian of Russia and equisetophyte evolution. In PDF. Geobios, 42: 513-523. See also here.
Note fig. 5: Neocalamites tubulatus nov. sp.; reconstruction of the stems with the lateral strobilus in attachment (left) and lateral shoot scar in the node (right).

! R. Neregato et al. (2022): Diversity and Stratigraphic Distribution of Sphenophytes in the Permian of the Paraná Basin, Brazil. In PDF, In: Iannuzzi, R., Rößler, R., Kunzmann, L. (eds.): Brazilian Paleofloras. Springer.
See also here.

R. Neregato and J. Hilton (2019): Reinvestigation of the Enigmatic Carboniferous Sphenophyte Strobilus Cheirostrobus Scott and Implications of In Situ Retusotriletes Spores. In PDF, Int. J. Plant Sci., 180: 811–833. See also here.

R. Neregato et al. (2017): New petrified calamitaleans from the Permian of the Parnaíba Basin, central-north Brazil, part II, and phytogeographic implications for late Paleozoic floras. In PDF, Review of Palaeobotany and Palynology, 237: 37–61. See also here.
Note fig. 2 (on PDF page 16): The proposed reconstruction of Arthropitys tocantinensis sp. nov., drawn by F. Spindler, Freiberg).

R Neregato et al. (2015): New petrified calamitaleans from the Permian of the Parnaíba Basin, central-north Brazil. Part I. In PDF, Review of Palaeobotany and Palynology, 215: 23-45. See also here.
Note fig. 3 (on PDF page 15): The proposed reconstruction of Arthropitys isoramis sp. nov., drawn by F. Spindler, Freiberg).

G. Nice and P. Sikkema: The Ancient Horsetail. In PDF, Purdue Extension Weed Science.

Dan Nickrent and Karen Renzaglia, Department of Plant Biology, Southern Illinois University at Carbondale: Land Plants Online, Horsetails - Phylum Equisetophyta.
This expired link is available through the Internet Archive´s Wayback Machine.

Karl J. Niklas & Tom Silva, Department of Plant Biology, Cornell University, Ithaca, NY: Introductory Botany. Review Topics, Review of Algae, Bryophytes, Pteridophytes- Common Links Between Each Group of Plants.
These expired links are available through the Internet Archive´s Wayback Machine.

J.M. Osborn and T.N. Taylor (1989): Structurally Preserved Sphenophytes from the Triassic of Antarctica: Vegetative Remains of Spaciinodum, gen. nov. PDF file, American Journal of Botany, 76: 1594-1601.
See also here.

Anthony Pigott, National Collection of Equisetum. Go to:
A Brief Introduction to Equisetum. Also worth checking out:
Cultivation of Horsetails. (based on an article first published 1988 in the Pteridologist 1: 209).
These expired links are still available through the Internet Archive´s Wayback Machine.
See likewise the new website attempt: http://equisetum.org/.

Anthony Pigott, The National Council for the Conservation of Plants and Gardens (NCCPG): Links. Here are a number of links to further information about horsetails on the Internet.
This expired link is now available through the Internet Archive´s Wayback Machine.

! Plantillustrations.org (by Max Antheunisse and Jan Koeman).
Plantillustrations.org is a completely non-commercial website. On top you see 2 search boxes at the right. The white one is for entering scientific names, the grey one for vernacular ones.
You may likewise navigate from:
the List of currently included artists.
Don't miss the useful link list

M. Pole and S. McLoughlin (2017): The first Cenozoic Equisetum from New Zealand. In PDF, Geobios, 50: 259–265. See also here.

Mike Pole, New Zealand:
Horsetail Marshes of the New Zealand Jurassic.

Henry Potonié, (1901): Die Silur und die Culm-Flora des Harzes und des Magdeburgischen (in German). Images of Calamites. See also here. The www.biolib.de project, Kurt Stüber, Max Planck Institut für Züchtungsforschung, Köln.

! C. Pott (2021): First record of intact equisetalean strobili from the Wealden (Lower Cretaceous) of the Isle of Wight, southern England. Free access, Fossil Imprint, 77: 43–52.

C. Pott et al. (2008): Sphenophytes from the Carnian (Upper Triassic) of Lunz am See (Lower Austria). PDF file, Jahrbuch der Geologischen Bundesanstalt Wien, 148 183-199.
Snapshot taken by the Internet Archive´s Wayback Machine.

! PPG I (2016); This project was organized by Eric Schuettpelz: A community-derived classification for extant lycophytes and ferns. Free access, Journal of Systematics and Evolution.

! K.M. Pryer et al. (2020): Using computer vision on herbarium specimen images to discriminate among closely related horsetails (Equisetum). Open access, Applications in plant sciences, 8.

K.M. Pryer et al. (2020): Using computer vision on herbarium specimen images to discriminate among closely related horsetails (Equisetum). Open access, Applications in Plant Sciences, 8: e11372. See also here (in PDF).

K.M. Pryer et al. (2001): Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants. Abstract, Nature, 409: 618-622.
! See also here (in PDF).

John A. Raven (2009): Horsetails get the wind up. New Phytologist, 184: 6-9. See also here (in PDF).

P.M. Rees and C.J. Cleal (2004): Lower Jurassic floras from Hope Bay and Botany Bay, Antarctica. In PDF, Palaeontological Association.
Still available via Internet Archive Wayback Machine. See also here.

Bernard Renault, 1881-1885 (provided by Gallica): Cours de botanique fossile fait au Muséum d´histoire naturelle.- Deuxième année (1882). Lépidodendrées, sphénophylles, astérophyllitées, annulariées, calamariées.

D. Rockenbach Boardman et al. (2016): A new genus of Sphenopsida from the Lower Permian of the Paraná Basin, Southern Brazil. In PDF, Review of Palaeobotany and Palynology, 233: 44–55. See also here and there.

R. Rößler et al. (2015): Der Versteinerte Wald Chemnitz - Momentaufnahme eines vulkanisch konservierten Ökosystems aus dem Perm (Exkursion L am 11. April 2015). PDF file, in German. The petrified forest of Chemnitz - A snapshot of an early Permian ecosystem preserved by volcanism. Jber. Mitt. oberrhein. geol. Ver., N.F. 97.

R. Rößler (2014): Die Bewurzelung permischer Calamiten: Aussage eines Schlüsselfundes zur Existenz freistehender baumförmiger Schachtelhalmgewächse innerhalb der Paläofloren des äquatornahen Gondwana. PDF file, in German. The roots of Permian calamitaleans - a key find suggests the existence of free-stemmed arborescent sphenopsids among the low latitude palaeofloras of Gondwana. Freiberger Forschungshefte, C 548.

! R. Rößler et al. (2012): The largest calamite and its growth architecture - Arthropitys bistriata from the Early Permian Petrified Forest of Chemnitz. In PDF, Review of Palaeobotany and Palynology, 185: 64-78.
The link is to a version archived by the Internet Archive´s Wayback Machine.

R. Rößler (2009): 300 Jahre Schatzsuche in Chemnitz: Die wissenschaftliche Grabung nach dem versteinerten Wald. In German (PDF file), Fossilien, 26.
Now available through the Internet Archive´s Wayback Machine.

! R. Rößler et al. (2008): Auf Schatzsuche in Chemnitz – Wissenschaftliche Grabungen `08. PDF file, in German. Veröffentlichungen des Museums für Naturkunde Chemnitz, 31: 05-44.
"... This contribution provides an overview and first results of the Natural History Museum’s scientific excavation,
[...] The whole tuff section provided plenty of fossil finds; some of the trunks still remained standing upright (in-situ) in growth position. The set of Permian age plants evidenced at this excavation belongs to a diverse mainly hygrophilous community made of cordaitaleans, medullosan seed ferns, calamitaleans and tree ferns. Of special scientific interest is a cordaitalean gymnosperm trunk showing branching in different height levels and some Arthropitys specimens one of these showing for the first time the diverse branched top of a calamitalean trunk ..."

Ronny Rößler & Robert Noll (website hosted by fossilien-journal.de): Calamitea COTTA 1832. Fossile Pflanze zwischen Historie und aktueller Forschung. PDF file, in German.
This expired link is available through the Internet Archive´s Wayback Machine.

R. Rößler and R. Noll (2006): Sphenopsids of the Permian (I): The largest known anatomically preserved calamite, an exceptional find from the petrified forest of Chemnitz, Germany. Abstract, Review of Palaeobotany and Palynology, 140: 145–162. See also here (in PDF).

R. Rößler, (2006): Einzigartig und dennoch ausgestorben - Die Schachtelhalm-Giganten des Perms (in German). In PDF, Fossilien, 23: 87-92. Provided by the Internet Archive´s Wayback Machine.

G.W. Rothwell and S.R. Ash (2015): Internal anatomy of the Late Triassic Equisetocaulis gen. nov., and the evolution of modern horsetails. Abstract, Journal of the Torrey Botanical Society, 142: 27-37.
See also here (in PDF).

Gar W. Rothwell, Department of Environmental and Plant Biology, Ohio University, Athens, OH: Vascular Plant Morphology. This course covers the structure, development, reproductive biology and relationships of vascular plants. The course is structured to emphasize the evolutionary changes that led to the diversity of modern tracheophytes. See for instance: Class Sphenopsida (PDF file).
These expired links are available through the Internet Archive´s Wayback Machine.

Patricia E. Ryberg et al. (2008): Development and ecological implications of dormant buds in the high-Paleolaltitude Triassic sphenophyte Spaciinodum (Equisetaceae). Abstract, Am. J. Bot., 95: 1443-1453. See also here.

Patricia E. Ryberg et al. (2007): Buds and Branching in the Triassic sphenophyte Spaciinodum collinsonii. Abstract, Botany & Plant Biology 2007, Botanical Society of America, Chicago.

Sächsische Landesamt für Umwelt und Geologie (2006): Das Döhlener Becken bei Dresden - Geologie und Bergbau. PDF file, in German. Bergbau in Sachsen, vol. 12. See especially PDF page 30: Makroflora und zugehörige "in situ"-Sporen (by M. Barthel).

! S. Saksena (1954): Reconstruction of the vegetative branches of Phyllotheca etheridgei and P. sahnii Saksena. In PDF, Palaeobotanist, 3: 51-53. See also here.
Note fig. 1 and 2: Reconstructions of Phyllotheca etheridgei and P. sahnii.

R. Sharma et al. (2019): Distribution of phytoliths in plants: a review. Open access, Geology, Ecology, and Landscapes, 3: 123-148.

! X. Shi (2016): Fossil plants and environmental changes during the Permian-Triassic transition in Northwest China. Thesis, Paleontology, Université Pierre et Marie Curie, Paris. See also here.

ScienceDirect (Elsevier’s premier platform):
! Navigate from the concept definition and subject overview website
Compiled information topic-by-topic. These pages are auto-generated by ScienceDirect using heuristic and machine-learning approaches to extract relevant information. Superbly done!

See for instance: ! Equisetaceae

! A.R. Smith et al. (2006). A classification for extant ferns. PDF file, Taxon 55: 705-731.

Department of Paleobiology, Smithsonian Institution, Washington, D.C.: Underground Carboniferous Forest (Riola mine, Illinois). A lycopsid tree stump and a pith cast of Calamites.
Now recovered from the Internet Archive´s Wayback Machine.

H.-C. Spatz et al. (1998): Biomechanics and functional anatomy of hollow-stemmed sphenopsids. I. Equisetum giganteum (Equisetaceae) Open access, American Journal of Botany, 85: 305-314.

N.A. Stanich et al. (2009): Phylogenetic diversification of Equisetum (Equisetales) as inferred from Lower Cretaceous species of British Columbia, Canada. In PDF, Am. J. Bot., 96: 1289-1299.
See also here.

Hans Steur, Ellecom, The Netherlands: Hans´ Paleobotany Pages. Plant life in the Silurian, Devonian, Carboniferous, Permian and Cretaceous. Go to: The horsetail tree Calamites, and
Wood of the horsetail tree Calamites.

Staatliches Museum für Naturkunde, Stuttgart, Germany.
Go to: Unterer Keuper (Lower Keuper, Lettenkeuper, Erfurt Formation, Ladinian, Triassic). In German.
! Don´t miss the photograph of the Equisetites arenaceus reconstructions in life position.
Wikipedia also provided a larger view of the Lettenkeuper diorama on its Batrachotomus website.

C. Strullu-Derrien et al. (2023): The Carboniferous (Serpukhovian) macroflora from the “Coteaux du Pont Barré”, Beaulieu-sur- Layon (Maine-et-Loire), South of the Armorican Massif, France. Open access, Botany Letters.
See also here (in PDF).

Ralph E. Taggart, Department of Botany and Plant Pathology/Department of Geological Sciences at Michigan State University, East Lansing:
! BOT335 Lecture Schedule. Some interesting chapters in terms of palaeobotany, e.g.
The First Vascular Land Plants;
Carboniferous Forests;
Arborescent Lycopods;
Psaronius: a Carboniferous tree-fern;
Carboniferous Horsetails;
Carboniferous Seed Ferns;
The Evolution of Conifers;
Cycadophytes, the True Cycads;
Mesozoic Cycadeoids;
Ginkgophytes;
North American Redwoods, Past and Present.
These expired links are available through the Internet Archive´s Wayback Machine.

! A.M.F. Tomescu and G.W. Rothwell (2022): Fossils and Plant Evolution: Structural Fingerprints and Modularity in the Evo-Devo Paradigm. Free access, Evodevo, 13.
See also here.
Note fig. 8: The realization that a reproductive program can be activated in the intercalary meristem of individual equisetacean internodes.

! A.M.F. Tomescu et al. (2017): Developmental programmes in the evolution of Equisetum reproductive morphology: a hierarchical modularity hypothesis. In PDF, Annals of Botany, 119: 489–505. See also: Sporangiophore development and Equisetum strobilus: how fossils and reproductive morphologies illuminate horsetail origins and homology. Free access, Content Snapshot.

A. Tosal et al. (2023): First report of silicified wood from a late Pennsylvanian intramontane basin in the Pyrenees: systematic affinities and palaeoecological implications. Free access, Papers in Palaeontology, 9. doi: 10.1002/spp2.1524.
"... The specimens correspond to two types of arborescent plants, a calamitacean Equisetales (Arthropitys sp.) and a Cordaitales (Dadoxylon sp.). They provide information not available from the adpression flora found in this locality, such as growth patterns, interactions with fungi, and the presence of tyloses ..."

A. Tosal et al. (2022): Plant taphonomy and palaeoecology of Pennsylvanian wetlands from the Erillcastell Basin of the eastern Pyrenees, Catalonia, Spain. In PDF, Palaeogeography, Palaeoclimatology, Palaeoecology, 605.
See also here.
"... A specimen of C. undulatus (50 cm long and 5 cm wide) was found charred and in an upright position within a pyroclastic bed intercalated in these shales ..."
Note figure 6; Plant taphonomic features. See especially:
Figure 6C: Charred Calamites undulatus stem crossing an ignimbrite deposit.

Tree of Life Web Project: Filicopsida (by Kathleen M. Pryer and Alan R. Smith).

V.P. Tverdokhlebov (2004): Buried Equisetites thickets from the Middle Triassic of the south Cis-Urals, Russia. In PDF, Neues Jahrbuch für Geologie und Palaontologie

! K. Vanneste et al. (2015): Horsetails Are Ancient Polyploids: Evidence from Equisetum giganteum. In PDF.
The link is to a version archived by the Internet Archive´s Wayback Machine.

A.S. Villalva et al. (2023): Systematic and organ relationships of Neocalamites (Halle) Vladimirovicz, and Nododendron (Artabe and Zamuner) emend. from the Triassic of Patagonia. Palaeobiogeographic, palaeoenvironments and palaeoecology considerations. Abstract, Review of Palaeobotany, 316.

Dave Walker, UK, Micscape Magazine: Horsetails: relic plants from prehistory. The attractive features of horsetails.

S.J. Wang et al. (2006): A large anatomically preserved calamitean stem from the Upper Permian of southwest China and its implications for calamitean development and functional anatomy. In PDF, Pl. Syst. Evol., 261: 229–244. See also here.

J. Watson (1983): Two Wealden species of Equisetum found in situ. PDF file, Acta Palaeontologica Polonica, 28: 265-269.

David T. Webb, University of Hawaii, Manoa, Honolulu: Sphenophytina.
This expired link is available through the Internet Archive´s Wayback Machine.

R. Weber (2008): Homomorfismo en Equisetaceae del Triásico: Asinisetum gen. nov., Equisetites aequecaliginosus Weber y conos asociados de Sonora, México (PDF file, in Spanish, with English and German abstracts). In: R. Weber (ed.): Plantas triásicas y jurásicas de México: Universidad Nacional Autónoma de México, Instituto de Geología, Boletín 115: 1-83.
Snapshot taken by the Internet Archive´s Wayback Machine.

R. Weber (2005): Equisetites aequecaliginosus sp. nov., ein Riesenschachtelhalm aus der spättriassischen Formation Santa Clara, Sonora, Mexiko. PDF file, (in German). Revue de Paléobiologie, Genève, 24: 331-364.

Wikipedia, the free encyclopedia:
Category:Equisetum.
Equisetidae.
Equisetaceae.
Equisetum.

Wikipedia, the free encyclopedia:
Batrachotomus.
! See especially the diorama of the Lettenkeuper swamp (Unterer Keuper, Erfurt Formation, Ladinian, Triassic). The Batrachotomus reconstruction in the background is surrounded by shafts of the horsetail Equisetites arenaceus. Photograph taken in the Staatliches Museum für Naturkunde, Stuttgart, Germany.

Student group, ?University of Alberta, WordPress @ Bio-Sci (a website provided for Biological Sciences):
! Paleobotany . Numerous photographs of fossil plants, taxonomically sorted, e.g.:
Sphenophytes.

! S. Yamanaka et al. (2012): Roles of silica and lignin in horsetail (Equisetum hyemale), with special reference to mechanical properties. In PDF, Journal of Applied Physics, 111.
See also here.

M.C. Zamaloa et al. (2022): The first fossil record of a giant horsetail (Equisetum, Equisetaceae) is from the Miocene of Patagonia, Argentina. In PDF, Andean Geology, 49: 273-287.
See also here.

Shuqin Zan et al. (2012): A new Neocalamites (Sphenophyta) with prickles and attached cones from the Upper Triassic of China. Abstract.

L. Zhang et al. (2020): New fossil material of Equicalastrobus (Equisetales) and associated leaves from the Late Triassic of Baojishan basin, Gansu Province, China. Abstract, Historical Biology. See also here (in PDF).

E. Zodrow and M. Mastalerz (2009): A proposed origin for fossilized Pennsylvanian plant cuticles by pyrite oxidation (Sydney Coalfield, Nova Scotia, Canada). PDF file, Bulletin of Geosciences, 84: 227-240.
! See fig. 12: In situ Calamites pith casts, Sydney Coalfield, Nova Scotia.

Chemistry Biology Pharmacy Information Center, ETH Hönggerberg, Zürich:
Chemistry, Biology and related disciplines in the WWW, Links > Chemistry & Biology > Botany > Cryptogams > Equisetaceae (in German).
Archived by the Internet Archive´s Wayback Machine.