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

! American Society of Plant Biologists: Education & Research - Bookmarks > Selaginella.
Website outdated. The link is to a version archived by the Internet Archive´s Wayback Machine.

K. Bauer et al. (2015): Lepacyclotes kirchneri n. sp. (Isoetales, Isoetaceae) aus dem unteren Jura von Oberfranken, Deutschland. In PDF, Berichte der Naturwissenschaftlichen Gesellschaft Bayreuth, 27: 429-443.

J. Bek and J.V. Frojdová (2023): Spore Evidence for the Origin of Isoetalean Lycopsids? Open access, Life, 13. https://doi.org/10.3390/life13071546.
Note figure 3: Phylogeny of isoetalean lycopsids.
Compare with figure 4: New scheme.
"... Spores with three apical papillae, reported as dispersed as well as in situ, were recorded continuously from the lower Silurian (Wenlockian) through the Devonian, Carboniferous, Permian, Mesozoic to Cenozoic era and form a phylogenetically independent lineage ..."

J.P. Benca (2022): Reconstructing Lycopsids Lost to the Deep Past. PDF file, In: Valérie Bienvenue et al. (eds.): Animals, Plants and Afterimages: The Art and Science of Representing Extinction (!free full text PDF).
See likewise here.
"... Accurate and conservative palaeobotanical reconstructions most often accompany scientific studies that can be difficult for the public to access. However, these works serve as indispensable guides for a growing number of palaeoartists undertaking more holistic ecosystem reconstructions that can, in turn, be presented to the public ..."

! J.P. Benca et al. (2014): Applying morphometrics to early land plant systematics: A new Leclercqia (Lycopsida) species from Washington State, USA. Free access, American Journal of Botany 101: 510–520. See also here, and there:
George Dvorsky, Gizmodo.com:
An Incredibly Life-Like Reconstruction Of A 400 Million-Year-Old Plant. Reconstruction of Leclercqia scolopendra.

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

C.M. Berry (2019): The evolution of the first forests in the Devonian. In PDF. See also here.
Note figure 1: Schematic timeline of known Devonian forest types.
Figure 2: Reconstruction of stand of Calamophyton (cladoxylopsid) trees (2—3 m high) based on fossils from Lindlar, Germany (Mid Eifelian age).
Figure 3: Reconstruction of forest showing upright cladoxylopsid trees (up to at least 8 m) and recumbent aneurophytaleans, from Gilboa, New York.
Figure 4: Reconstruction of forest of lycopsids with cormose bases and attached rootlets, from Munindalen, Svalbard.

C.M. Berry (2019): Palaeobotany: The Rise of the Earth’s Early Forests. Free access, Current Biology, 29: R792-R794.
Note figure 1: The ecology and appearance of known early forests.

C.M. Berry and J.E.A. Marshall (2015): Lycopsid forests in the early Late Devonian paleoequatorial zone of Svalbard. Free access, Geology, 43: 1043-1046.

B. Bomfleur et al. (2011): Macrofossil evidence for pleuromeialean lycophytes from the Triassic of Antarctica. PDF file, Acta Palaeontol. Pol., 56: 195-203. See also here.

! K. Boyce and W.A. DiMichele (2018): Fast or slow for the arborescent lycopsids?: Response to Thomas & Cleal (2018) 'Arborescent lycophyte growth in the late Carboniferous coal swamps'. New Phytologist, 218: 891–893. See also here.

Bill Chaloner & Geoff Creber, Royal Holloway, University of London (website hosted by The International Organisation of Palaeobotany, IOP): Unexpected occurrences, An unexpected exposure: Pleuromeia.

! M.J.M. Christenhusz et al. (2011): A linear sequence of extant families and genera of lycophytes and ferns. PDF file, Phytotaxa, 19: 7-54.

B.-Y. Chen et al. (2022): Anatomy of Stigmaria asiatica Jongmans et Gothan from the Asselian (lowermost Permian) of Wuda Coalfield, Inner Mongolia, North China. In PDF, Palaeoworld, 31: 311–323.
See also here.

Curtis Clark, Biological Sciences Department, California State Polytechnic University, Pomona: Plant Morphology, and Resource. Go to: Lab 10: Lycophyta, Psilotophyta (PDF file).
These expired links are available through the Internet Archive´s Wayback Machine.

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

C.J. Cleal et al. (2016): Spondylodendron pranabii — the dominant lycopsid of the late Mississippian vegetation of the Kashmir Himalaya. Abstract, Alcheringa: An Australasian Journal of Palaeontology, 40. See also here (in PDF).

I. Cojocaru (2010): Orientations in Macrotaxonomy. PDF file.

Compiled by P.R. Crane et al. (page hosted by the Department of Integrative Biology, University of California, Berkeley):
LYCOPHYTES. Compiled at the 1995 Berkeley meeting of the GPPRCG and modified based on broader input at the 1996 Seattle meeting.
Still available through the Internet Archive´s Wayback Machine.

Jim Croft, The Australian National Herbarium: A classification of the ferns and their allies - a work in progress. Snapshot taken by the Internet Archive´s Wayback Machine.
This classification of the genera of ferns and their allies is a loose, perhaps tenuous, concensus of a number of published systems, some of which are available on the web. It tries to reflect contemporary views on phylogenetic relationships and as such will change from time to time.

M.P. D'Antonio and F. Herrera (2024): New Evidence of Unequal Branching in Stigmaria ficoides (Lycopsida). Open access, International Journal of Plant Sciences, 185.
"... Stigmaria ficoides is the main form species of rooting organ for late Paleozoic arborescent lycopsids in the families Diaphorodendraceae and Lepidodendraceae.
[...] we report two S. ficoides specimens based on the presence of the diagnostic rootlet scar pattern ..."

M.P. D'Antonio and C.K. Boyce (2021): Secondary phloem in arborescent lycopsids. Open access, New Phytologist, 232: 967-972.

M.P. D'Antonio et al. (2021): Primary tissues dominated ground-level trunk diameter in Sigillaria: evidence from the Wuda Tuff, Inner Mongolia. In PDF, Journal of the Geological Society. See also here.
Note figs. 1-4: in situ stump casts of Sigillaria from the earliest Permian.

M.P. D'Antonio and C.K. Boyce (2020): Arborescent lycopsid periderm production was limited. Free access, New Phytologist, 228: 741-751.
"... we argue that physiological limitations would have prohibited the production of thick periderm
[...] The large amount of arborescent lycopsid periderm in Middle Pennsylvanian coals represents taphonomic enrichment rather than a true anatomical signal ..."

S. Deng et al. (2022): A new species of Pleuromeia (Lycopsid) from the upper Middle Triassic of Northern China and discussion on the spatiotemporal distribution and evolution of the genus. Abstract, Geobios.
"... Spatiotemporal distribution of Pleuromeia indicates that the genus first appeared in the Induan (Early Triassic) in North China, occurred widespread and flourished in both Laurasia and Gondwana during the Olenekian (late Early Triassic), declined from the Anisian (early Middle Triassic), survived in the Ladinian in North China, and may have gone extinct as early as the end of the Middle Triassic. ..."

S. Deng et al. (2022): Lycopsid Annalepis Fliche from the Middle Triassic of the Ordos Basin, North China and reviews of the genus. Abstract, Review of Palaeobotany and Palynology.
! "... Due to its relatively short geological ranges, fairly wide geographic distributions and strict palaeoecological requirements, this genus is important in stratigraphical correlation and palaeoenvironmental interpretation. ..."

! Michel Desfayes, Fully, Switzerland ("the irrepressible compiler"):
Bibliography of Isoetes (2006). Including fossil species.
Now recovered from the Internet Archive´s Wayback Machine.

W.A. DiMichele et al. (2022): Stigmaria: A Review of the Anatomy, Development, and Functional Morphology of the Rootstock of the Arboreous Lycopsids. Abstract, International Journal of Plant Sciences.
"... We reevaluate the conventional view that the rootlets were abscised, ..."
"... In soil, rootlets improved anchorage, whereas in open water, largely hollow mature roots may have enhanced stigmarian system buoyancy and nucleated floating peat mats. ..."

W.A. DiMichele et al. (2013): Growth habit of the late Paleozoic rhizomorphic tree-lycopsid family Diaphorodendraceae: Phylogenetic, evolutionary, and paleoecological significance. Open access, American Journal of Botany, 100: 1-22.

W.A. DiMichelle and R.A. Bateman (1996): The rhizomorphic lycopsids: a case-study in paleobotanical classification. PDF file, Systematic Botany, 535-552.
See also here.

W.A. DiMichele et al. (1996): A drowned lycopsid forest above the Mahoning coal (Conemaugh Group, Upper Pennsylvanian) in eastern Ohio, USA. PDF file, International Journal of Coal Geology, 31.
See also here.

M.T. Dunn et al. (2012): Winslowia tuscumbiana gen. et sp. nov. (Chaloneriaceae): A Cormose, Heterosporous, Ligulate Lycopsid Reconstructed from the Inside Out from the Pride Mountain Formation (Late Mississippian/Serpukhovian) of Northern Alabama. Abstract, International Journal of Plant Sciences, 173: 96-111.

R.L. Dunstone and G.C. Young (2019): New Devonian plant fossil occurrences on the New South Wales South Coast: geological implications. In PDF, Australian Journal of Earth Sciences, 66. See also here.

Z. Feng et al. (2024): Fossil evidence for silica biomineralisation in Permian lycophytes. Open access, National Science Review,

Z. Feng et al. (2020): From rainforest to herbland: New insights into land plant responses to the end-Permian mass extinction. Free access, Earth-Science Reviews.
Note fig. 8: Tomiostrobus sinensis Feng, whole plant reconstruction.
Note fig. 9: Reconstructions of the late Permian and Early Triassic vegetation in Southwest China.

X. Gao et al. (2022): Re-study of Guangdedendron micrum from the Late Devonian Xinhang forest. Free access, BMC Ecology and Evolution, 22.
Note the reconstruction in fig. 6.

Google Directory:
Science > Biology > Flora and Fauna > Plantae > Lycopodiophyta.
Link directory, with ratings (Google page rank).
This expired link is available through the Internet Archive´s Wayback Machine.

! L. Grauvogel-Stamm and B. Lugardon, (2001): The Triassic Lycopsids Pleuromeia and Annalepis: Relationships, Evolution, and Origin. PDF file, American Fern Journal 91: 115-149.
See also here.
Note fig. 2: Comparative growth habit of the Paleozoic and Triassic Pleuromeia-like lycopsids and the extant Isoetes.
Fig. 6. Comparative morphology of the sporophylls of the Annalepis-type and related genera.

! W.A. Green (2010): The function of the aerenchyma in arborescent lycopsids: evidence of an unfamiliar metabolic strategy. PDF file, Proc. R. Soc., B, 277: 2257-2267.

F. Herrera et al. (2022): A permineralized Early Cretaceous lycopsid from China and the evolution of crown clubmosses. In PDF, New Phytologist, 233: 2310-2322.
See also here.

A.J. Hetherington and L. Dolan (2019): Rhynie chert fossils demonstrate the independent origin and gradual evolution of lycophyte roots. Abstract, Current opinion in plant biology, 47: 119-126. See also here and there (in PDF).

A. Hetherington (2017): Evolution and morphology of lycophyte root systems. In PDF, Thesis, St Catherine’s College, Department of Plant Sciences, University of Oxford. See also here.

! A.J. Hetherington et al. (2016). Networks of highly branched stigmarian rootlets developed on the first giant trees. Free access, Proceedings of the National Academy of Sciences, USA, 113: 6695–6700.

! A.J. Hetherington and L. Dolan (2016): The evolution of lycopsid rooting structures: conservatism and disparity. In PDF, New Phytologist.

Monte Hieb and Harrison Hieb: Plant Fossils of West Virginia. Fossil Plants of the Middle Pennsylvanian Period. Go to: Lycopods.
These expired links are available through the Internet Archive´s Wayback Machine.

M. Hrabovský (2020): LEAF EVOLUTION AND CLASSIFICATION. 1. LYCOPODIOPSIDA. In PDF, Acta Botanica Universitatis Comenianae, 55.

K.R. Johnson (2007): Paleobotany: Forests frozen in time. In PDF, Nature, 447.
Fig. 1 shows the reconstruction of a lycopsid forest.
Provided by the Internet Archive´s Wayback Machine.

M. Alan Kazlev, Palaeos, Class Lycopsida. Snapshot taken by the Internet Archive´s Wayback Machine. Go to: Order Pleuromeiales.

M. Alan Kazlev and Mikko Haaramo, Palaeos, The systematics of the plant kingdom, Lycopsids. Go to: Lycophytina cladogram (various sources).
Snapshots taken by the Internet Archive´s Wayback Machine.

! Kelber, K.-P. (2003): Sterben und Neubeginn im Spiegel der Paläofloren. PDF file (17 MB!), in German. Plant evolution, the fossil record of plants and the aftermath of mass extinction events. pp. 38-59, 212-215; In: Hansch, W. (ed.): Katastrophen in der Erdgeschichte - Wendezeiten des Lebens.- museo 19, Heilbronn.
Please take notice of figure 9 (PDF page 10): A reconstruction of Pleuromeia sternbergii and the in situ occurrence of casts of stems of this species in a red sandstone of the early Triassic Period, combined with a landscape sketch.

D. Klärner (2016), Frankfurter Allgemeine (FAZ): Die schicksalhaften Wälder. In German.
About P.A. Hochuli et al. (2016): Severest crisis overlooked ...

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.

V.A. Krassilov and Y.D. Zakharov (1975): Pleuromeia from the Lower Triassic of the Far East of the USSR. In PDF, Review of Palaeobotany and Palynology. See also here.

E. Kustatscher et al. (2010): Lycophytes from the Middle Triassic (Anisian) locality Kühwiesenkopf (Monte Prà della Vacca) in the Dolomites (northern Italy). Free access, Palaeontology, 53: 595-626.

E. Larsén (2024): Phylogeny and macroevolution in Isoetes (Isoetales). In PDF, Dissertation, Department of Ecology, Environment and Plant Sciences, Stockholm University.
See here as well.

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

C.V. Looy et al. (2021): Proliferation of Isoëtalean Lycophytes During the Permo-Triassic Biotic Crises: A Proxy for the State of the Terrestrial Biosphere. In PDF, Front. Earth Sci. 9: 615370. See also here (open access).

C. Looy and I. Duijnstee (2010), Behind the scenes, Museum of Paleontology, University of California, Berkeley: Museum nomads. About Pleuromeia fossils in the Museum für Naturkunde, Berlin.

Cindy V. Looy, Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C.: Ecological success of Early Triassic isoetaleans. A reconstruction of Pleuromeia sternbergi from the Early Triassic.
Available through the Internet Archive´s Wayback Machine.

Department of Botany, University of Wisconsin, Madison: Plant Systematics Collection. This web site provides structured access to a teaching collection of plant images representing over 250 families and 1000 genera of vascular plants. Go to: Lycophyta. Lycopodiaceae, Selaginellaceae, Isoetaceae.

Janet Marinelli, Brooklyn Botanic Garden; Plants & Gardens News Volume 18, Number 2; 2003: Power Plants — The Origin of Fossil Fuels. A palaeovegetation reconstruction by Maud H. Purdy.
See also here. The link is to a version archived by the Internet Archive´s Wayback Machine.

G. McLean (2017): A 'mystery fossil' is evidence for massive Devonian trees in Australia. In PDF, Records of the Australian Museum, 69: 101–118. See also here.
Note figure 10: A possible taphonomic process experienced by the Griffith specimen.

S. McLoughlin et al. (2015): Paurodendron stellatum: A new Permian permineralized herbaceous lycopsid from the Prince Charles Mountains, Antarctica. In PDF, Review of Palaeobotany and Palynology, 220: 1-15. Reconstruction on PDF page 11.
See also here.

! M.-C. Meng et al. (2015): Vegetative Characters, Growth Habit and Microsporangiate Strobilus of Lycopsid Minostrobus chaohuensis. PLoS ONE, 10.

John Mieles, Department of Earth and Environmental Sciences, University of Rochester: Evolution of the Earth, Student Webpages, Divisions Lycophyta and Sphenophyta in the Late Paleozoic.
Website outdated, download a version archived by the Internet Archive´s Wayback Machine.

P. Moisan and S. Voigt (2013): Lycopsids from the Madygen Lagerstätte (Middle to Late Triassic, Kyrgyzstan, Central Asia). Abstract, Review of Palaeobotany and Palynology, 192: 42-64. See also here.

P. Moisan et al. (2012): Lycopsid-arthropod associations and odonatopteran oviposition on Triassic herbaceous Isoetites. In PDF, Palaeogeography Palaeoclimatology Palaeoecology.
See also here.
! Don´t miss table 1, the compilation of evidence for oviposition in the fossil record.

T.E. Mottin et al. (2022): A glimpse of a Gondwanan postglacial fossil forest. In PDF, Palaeogeography, Palaeoclimatology, Palaeoecology, 588. See also here.

! Palaeobotanical Research Group, Münster, Westfälische Wilhelms University, Münster, Germany. History of Palaeozoic Forests, FOSSIL AND EXTANT LYCOPHYTES. Link list page with rankings and brief explanations. Images of Lepidodendron aculeatum, Lepidophyllum, Lepidophylloides, Cyperites bicarinatus, Lepidostrobus, Lepidostrobophyllum, Lepidostrobophyllum lanceolatum, Lepidophloios laricinus, Lepidophloios.

! Terence M. Murphy, Thomas L. Rost and Michael G. Barbour (2015), University of California, Davis, CA:
Plant Biology. Lecture notes, in PDF.
Please take notice: Book announcement.
See for instance: Bryophytes.
The Early Tracheophytes.
These expired links are now available through the Internet Archive´s Wayback Machine.

Dennis C. Murphy, ("Devonian Times", a paleontology web site featuring Red Hill): Who's Who at Red Hill, unidentified cormose lycopsid (Lycopsid Tree), cf. Lepidodendropsis sp. (Lycopsid Tree), and More about Lycopsids.

S.V. Naugolnykh (2013): The heterosporous lycopodiophyte Pleuromeia rossica Neuburg, 1960 from the Lower Triassic of the Volga River basin (Russia): organography and reconstruction according to the "Whole-Plant" concept. In PDF, Wulfenia, 20: 1-16.

! S.V. Naugolnykh (2012): Sporophyll morphology and reconstruction of the heterosporous lycopod Tomiostrobus radiatus Neuburg emend. from the Lower Triassic of Siberia (Russia). In PDF, The Palaeobotanist, 61: 387-405.

Dan Nickrent and Karen Renzaglia, Department of Plant Biology, Southern Illinois University at Carbondale: Land Plants Online, Lycophytes - Phylum Lycopodiophyta. Snapshot taken by 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.

Karl J. Niklas & Tom Silva, Department of Plant Biology, Cornell University, Ithaca, NY: Introductory Botany. Review Topics, Megasporogenesis and Megagametogenesis: A Review.
Now available through the Internet Archive´s Wayback Machine.

! Old Dominion University, Norfolk, VA: Isoetes. Including the Bibliography of Isoetes and the Isoetes Spore Library (PDF file).

S. Oplustil (2010): Contribution to knowledge on ontogenetic developmental stages of Lepidodendron mannebachense Presl, 1838. PDF file, Bulletin of Geosciences.

! H.W. Pfefferkorn (2004): The complexity of mass extinction. Commentary, PNAS, 101: 12779-12780.
Take notice of figure 2: A reconstruction of the herbaceous lycopsid Pleuromeia and the in situ occurrence of casts of stems of this species in a red sandstone of the early Triassic Period, combined with a landscape sketch with this plant and a fern species.

! K.B. Pigg (2001): Isoetalean Lycopsid Evolution: from the Devonian to the Present. PDF file, American Fern Journal, 91: 99-114. See also here (abstract).

! 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.

! 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.

B.R. Pratt and J. van Heerde (2017): An arborescent lycopsid stem fragment from the Palliser Formation (Famennian) carbonate platform, southwestern Alberta, Canada, and its paleogeographic and paleoclimatic significance. In PDF, Canadian Journal of Earth Sciences, 54: 141-145. See also here (abstract).

The Pteridophyte Phylogeny Group (PPG), Smithsonian National Museum of Natural History. PPG aims to produce, and continually update, a community-derived classification for lycophytes and ferns - based on the understanding of phylogeny - at the family and genus levels.

! M. Qin et al. (2024): In situ forest with lycopsid trees bearing lobed rhizomorphs from the Upper Devonian of Lincheng, China. Free access, PNAS Nexus, 3. pgae241, https://doi.org/10.1093/pnasnexus/pgae241.
Note figure 7: Reconstruction of Heliodendron’s rooting system.
"... The Devonian witnessed the transformation from clastic nonlycopsid dominated forests to Carboniferous swampy forests dominated by giant lycopsid trees. These trees form a multigenerational community, as shown by the in situ preserved stems at various levels ..."

E. Reeves et al. (2023): Historic palaeobotanical collection reveals in situ microspores and pollen from Early Carboniferous (Tournaisian) ovules from the Ballagan Formation of Scotland. In PDF, Review of Palaeobotany and Palynology, 308.
See also here.

Bernard Renault, 1881-1885 (provided by Gallica): Cours de botanique fossile fait au Muséum d'histoire naturelle.- Première année (1881). Cycadées, zamiées, cycadoxylées, cordaïtées, poroxylées, sigillariées, stigmariées.

! G.J. Retallack (1997): Earliest Triassic origin of Isoetes and quillwort evolutionary radiation. PDF file, Journal of Paleontology, 71: 500-521.
See also here.
! Note figure 1: Comparison of Triassic lycopsid sporophylls.

G. Retallack (1975): The life and times of a Triassic lycopod. PDF file, Alcheringa.

M.A. Romanova et al. (2023): All together now: Cellular and molecular aspects of leaf development in lycophytes, ferns, and seed plants. In PDF, Front. Ecol. Evol., 11: 1097115. doi: 10.3389/fevo.2023.1097115. See also here.
"... To understand leaf origin in sporophytes of land plants, we have combined the available molecular and structural data on development of leaves with different morphologies in different plant lineages ..."
Note figure 10: Phylogenetic tree for land plants and their structural and regulatory innovations.
Figure 11: Hypothesized scenario for the evolutionary emergence of leaves in lycophytes.

! G.W. Rothwell And R. Stockey (2023): Anatomically preserved early Cretaceous lycophyte shoots; enriching the paleontological record of Lycopodiales and Selaginellales. In PDF, Acta Palaeobotanica, 63: 119–128.
See also here.
"... The Selaginella specimens represent the first anatomically preserved Selaginellales with excellent internal cellular preservation in the fossil record
[...] These fossils document that species with diagnostic internal anatomy of modern Lycopodiales and Selaginellales evolved no later than the Valanginian of the early Cretaceous ..."

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. Go to: Class Lycopsida. (PDF file).

! A.R. Schmidt et al. (2022): Selaginella in Cretaceous amber from Myanmar. Open access, Willdenowia, 52: 179–245.
Breathtaking photographs showing mid-Cretaceous plant remains in amber!

H. Schneider and E. Schuettpelz (2016): Systematics and evolution of lycophytes and ferns: Editorial. Abstract, Journal of Systematics and Evolution, 54: 561–562. See also here (in PDF).

E. Schuettpelz and S.B. Hoot (2006): Inferring the Root of Isoetes: Exploring Alternatives in the Absence of an Acceptable Outgroup. Abstract, Systematic Botany, 31: 258-270.

! Alan R. Smith, Kathleen M. Pryer, Eric Schuettpelz, Petra Korall, Harald Schneider, & Paul G. Wolf (2006). A classification for extant ferns. PDF file, Taxon 55: 705–731.
This expired link is available through the Internet Archive´s Wayback Machine.

V. Spencer et al. (2020): What can lycophytes teach us about plant evolution and development? Modern perspectives on an ancient lineage. Open access, Evolution & Development, 23: 174–196.

A.R.T. Spencer and C. Strullu-Derrien (2017): Photogrammetry: preserving for future generations an important fossil site situated in Maine-et-Loire (France). Poster, in PDF.
Large 1–9m lycoposid stems and branches, rhizomes and leaves, preserved as carbonized adpressions or 3D mold/casts.

R. Spiekermann et al. (2018): A remarkable mass-assemblage of lycopsid remains from the Rio Bonito Formation, lower Permian of the Paraná Basin, Rio Grande do Sul, Brazil. In PDF, Palaeobiodiversity and Palaeoenvironments, 98: 369–384. See also here.

Hans Steur, Ellecom, The Netherlands: Hans´ Paleobotany Pages. Plant life in the Silurian, Devonian, Carboniferous, Permian and Cretaceous. Go to: The clubmoss tree Sigillaria, Identification table Sigillaria, and The clubmoss tree Lepidodendron.

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.

! B.A. Thomas and C.J. Cleal (2022): A reassessment of the leafy shoots of Pennsylvanian-age arborescent lycopods. Open acces, Botany Letters, DOI: 10.1080/23818107.2022.2101517.
See also here.
Note figure 1: Reconstruction of arborescent lycopsids of the Pennsylvanian-age palaeotropical coal swamps of Euramerica.

! B.A. Thomas and C.J. Cleal (2018): Arborescent lycophyte growth in the late Carboniferous coal swamps. Free access, New Phytologist, 218: 885–890.

! B.A. Thomas and L.J. Seyfullah (2015): Stigmaria Brongniart: a new specimen from Duckmantian (Lower Pennsylvanian) Brymbo (Wrexham, North Wales) together with a review of known casts and how they were preserved. Abstract, Geological Magazine, 152: 858–870. See also here (in PDF).

Angelo Troia and Antonella Troia, Laboratorio Fisiologia Vegetale, Dip. Scienze Botaniche dell´Università, Palermo: The Isoëtes Page. Go to: The Isoëtes Page. A bibliography.
These expired links are available through the Internet Archive´s Wayback Machine.

J.H.A. van Konijnenburg-van Cittert et al. (2016): New data on Selaginellites coburgensis from the Rhaetian of Wüstenwelsberg (Upper Franconia, Germany). Abstract, Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 280. See also here (Open Access in DiVA).

A. Vasco et al. (2016): Challenging the paradigms of leaf evolution: Class III HD-Zips in ferns and lycophytes. In PDF, New Phytologist, 212: 745–758. See also here.

M. Viney et al. (2019): A Silicified Carboniferous Lycopsid Forest in the Colorado Rocky Mountains, USA. Open access, Geosciences,9. doi:10.3390/geosciences9120510

S.I. Vogel et al. (2011): The Effects of Fire on Lycopodium digitatum strobili. In PDF, Jeffersoniana, 27: 1-9.

! D. Wang et al. (2019): The Most Extensive Devonian Fossil Forest with Small Lycopsid Trees Bearing the Earliest Stigmarian Roots. Current Biaology, 29: 2604-2615. See also here (in PDF).
Note figure 6: Reconstruction of Guangdedendron.
! Note figure 7: Reconstruction of Xinhang Forest Landscape.
Also worth checking out: Ältester fossiler Wald Asiens entdeckt. Scinexx, in German.

U. Weber (1922): Zur Anatomie und Systematik der Gattung Isoëtes L. (On the anatomy and systematics of the genus Isoëtes L.) In PDF, Hedwigia 63: 219-262.

M. Wei-Haas (2019): Bizarre Fossils Reveal Asia's Oldest Known Forest. National Geographic Australia.

C.H. Wellman et al. (2009): Spore wall ultrastructure in the early lycopsid Leclercqia (Protolepidodendrales) from the Lower Devonian of North America: Evidence for a fundamental division in the lycopsids. Free access, American Journal of Botany, 96: 1849-1860.

N. Wikström et al. (2022): No phylogenomic support for a Cenozoic origin of the “living fossil” Isoetes. OPen access, American Journal of Botany.

J.P. Wilson et al. (2023): Physiological selectivity and plant–environment feedbacks during Middle and Late Pennsylvanian plant community transitions. Open access, Geological Society, London, Special Publications, 535: 361-382.
"... We find that three Pennsylvanian plant lineages – the medullosans, arborescent lycopsids and Sphenophyllum – contain high hydraulic conductivity but are vulnerable to drought-induced damage, whereas others are resistant, including stem group tree ferns and coniferophytes ..."

D. Wood et al. (2020): Phylogenomics indicates the “living fossil” Isoetes diversified in the Cenozoic. Open access, Plos One, 15.
"... genomic analyses coupled with a careful evaluation of the fossil record indicate that despite resembling forms from the Triassic, extant Isoetes species do not represent the remnants of an ancient and widespread group, but instead have spread around the globe in the relatively recent past. ..."

X. Yang et al. (2023): Spatial transcriptomics of a lycophyte root sheds light on root evolution. Abstract, Current Biology, 33.

J. Yu et al. (2010): Annalepis, a pioneering lycopsid genus in the recovery of the Triassic land flora in South China. In PDF, Comptes Rendus Palevol., 9: 479-486. See also here.

Y. Zhang and G. Sun (2023): Recent advance on study of Pleuromeia. In PDF, Global Geology, 26.
See also here.

Y. Zhang et al. (2020): Pleuromeia discovered from the Middle Triassic Linjia Formation of Benxi, Northeast China. Abstract, Palaeoworld. See also here (in PDF).