DOCSLIB.ORG

Lyginopteris Oldhamia Class Cycadopsida Order Pteridospermales Family Lyginopteridaceae Genus Lyginopteris Species L.Oldhamia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Lyginopteris Oldhamia Class Cycadopsida Order Pteridospermales Family Lyginopteridaceae Genus Lyginopteris Species L.Oldhamia Prepared for B.Sc. Part II Botany Hons. by Prof.(Dr.) Manorma Kumari Lyginopteris oldhamia Class Cycadopsida Order Pteridospermales Family Lyginopteridaceae Genus Lyginopteris Species L.oldhamia Lyginopteris is well known genus in the family Lyginopteridaceae. It was earlier known as Calymmatotheca hoeninghausii. Williamson, Scott, Brongniart, Binney, Potonie and Oliver and Scott described this genus in detail. It was found in abundance in the coal ball horizon of Lancashire and Yorkshire. Various parts of the plants were discovered and named separately. They were later found to be different organs of the same plants Lyginopteris due to presence of similar type of capitate gland on them (except roots). Various parts are: Leaves Sphenopteris hoeninghausii Stems Lyginopteris oldhamia Petioles Rachiopteris aspera Roots Kaloxylon hookeri Seeds Lagenostoma lomaxi Morphological Features The stem of Lyginopteris oldhamia was long aerial and radially symmetrical varying in diameter from 2mm to 4cm. It was frequently branched and bore adventitious roots that were probably prop roots that supported the weak stems. The leaves were spirally arranged and up to 0.5 metre long. The leaves were bipinnate to tripinnate. The pinnae had pinnules or leaflets and were present at right angles to the rachis. The rachis and petiole were studded with capitate glands. Lyginopteris oldhamia: A. Showing external character; B. Frond bearing pollen sac; C. Frond bearing seeds. 2 Anatomy Stem: The transverse sections of the stem show nearly circular outline. Outer layer is epidermis, next to it is many layered cortex. Outer cortex contains radially broadened fibrous strands that forms a vertical network. It provides mechanical strength to the weak stem. The inner cortex consists of parenchymatous cells. The pericycle present just inner to the cortex, consist of short cells and a number of thick walled or sclerotic cells with dark contents. Five mesarch primary vascular bundles separated by parenchymatous areas are present. The phloem is towards the outer side in each vascular bundle and consists of irregularly arranged small cells. Next to it, is the cambium that is well preserved in some specimens. The xylem consists of tracheids. The protoxylem tracheids have spiral thickenings. Centripetal tracheids of the metaxylem have multiseriate bordered pits while the centrifugal tracheids are scalariform. The pith is large and parenchymatous. Some thick-walled cells, called sclerotic nests are scattered throughout the pith. Several distinctly mesarch leaf traces are quite prominent. One leaf trace traverses through the petiole and branches into two parts to supply the forking rachis. The secondary structure of the stems exhibits the presence of periderm just inner to the two' cortical layers. The primary phloem gets crushed and inner to this the cylinder of the secondary vascular tissue is present and it surrounds the primary xylem. Several medullary rays are in this region. The leaf traces interrupt the cylinder of secondary vascular tissue. Many large and small cells are alternately present in the secondary phloem. The cambium and then secondary xylem are present inner to the secondary phloem region. The secondary xylem consists of large tracheids with multiseriate bordered pits arranged on the radial walls. (A): Lyginopteris oldhamia A.T.S. (B): L.S. of Primary vascular bundle of primary stem Leaf The pinnules are covered with a distinct layer of upper and lower epidermises. The upper epidermis is cutinised and the cuticle is very resistant and 3 well preserved. There are well defined palisade and spongy tissues that made up the mesophyll tissue. The stomata are restricted to the underside. Lyginopteris oldhamia T.S. stem showing secondary structure Part of T.S. Pinna of Sphenopteris hoeninghausii Root The transverse section of root is roughly circular in outline. Cortex is differentiated into outer cortex and inner cortex. Outer cortex made up of 2-3 layers of thin walled cells with scanty content. The inner cortex is 4-6 layered whose cells were full of dense contents. These are considered to be muscilaginous in nature. The endodermis and pericycle are clearly observed. Root possess many primary xylem strands alternating with an equal number of phloem strands. The xylem is exarch. The pith is scanty. The branches of root develop opposite the 4 protoxylem points. The large roots show a secondary wood. It is traversed by large rays that always lie opposite the protoxylem groups. T.S. Root of Lyginopteris oldhamia All the parts of the plant except the root are covered by numerous stalked glandular outgrowths. These glandular outgrowths are flask-shaped and may be up to 3mm high. They are not supplied by any vascular strand and are, therefore, considered as mere emergences. Each outgrowth bears an apical globular head that consists of a number of thin-walled secretory cells. It ranges in diameter from 0.12-0.4mm. Below the secretory head is a stalk made up of several layers of parenchyma cells. These are capitate glands. Reproductive Structure Lyginopteris oldhamia was heterosporous, and its ovules and seeds were enclosed within well protective cupules. Kidston (1905) discovered the impressions of Crossotheca in connection with the leaves of Sphenopteris hoeninghausii and thus it was concluded that Crossotheca is the microsporangium of Lyginopteris because the leaves of Lyginopteris were described under the name Sphenopteris hoeninghausii. The ovules and seeds of Lyginopteris were described under the name Lagenostoma lomaxi. Arnold (1947) stated that the microsporangiate structures of Lyginopteris belongs to Telangium. Some other workers have also shown doubts on the validity of Crossotheca being the microsporangium of Lyginopteris. 5 Microsporangium Crossotheca hoeninghausii has been described as the microsporangia of Lyginopteris. Six to seven bilocular, pendant microsporangia were present on more or less peltate fertile pinnules called microsporophylls. Each microsporangium was about 3mm in length and its dehiscence was longitudinal. Microspores were present in the cavities of microsporangia, sometimes even in tetrads. Each microspore had a thick rough exine and attained a diameter of 50 to 70 micron. They have tri-radiate markings (trilete). The sporangia lack annulus and resemble those of Cycas. There is no evidence of pollen tubes and so sperm must have been motile. Lyginopteris oldhamia, part of a frond bearing microsporangia Ovule and Seed Olive and Scott (1903) describe Lyginopteris oldhamia seeds as Lagenostoma lomaxii. Seed was a small, barrel-shaped structure measuring 5 to 6mm in length and about 4mm in width. Each seed was surrounded by a cupule present at the end of the slender rachis (Jongmans, 1930). Rachis was also covered by capitate glands. The seeds and the cupule are known only in petrified condition. The ovule is orthotropous with a stout integument. The integument is not lobed and forms a single complete sheath penetrated at the apex by a narrow micropyle. The integument is fused with the nucellus except near the micropylar end where it is free from the nucellus and forms a canopy. This canopy part is divided into nine loculi with a vascular bundle extending into each. The integument shows two distinct regions, the external sclerotesta which is hard and stony and an inner fleshy endotesta. External to the integument, the ovule is partially enclosed by a lobed cupule which is studded with numerous 6 glandular outgrowths. The nucellus apex has a hollow pollen chamber or Lagenostome. V.S. of Ovule of Lyginopteris oldhamia The seed of Lyginopteris oldhamia ……… .
Load more

Recommended publications
  • A Comparative Study of the Primary Vascular System Of
    Amer. J. Bot. 55(4): 464-472. 1!16'>. A COMPARATIVE STUDY OF THE PRIMARY VASCULAR SYSTE~1 OF CONIFERS. III. STELAR EVOLUTION IN GYMNOSPERMS 1 KADAMBARI K. NAMBOODIRI2 AND CHARLES B. BECK Department of Botany, University of Michigan, Ann Arbor ABST RAe T This paper includes a survey of the nature of the primary vascular system in a large number of extinct gymnosperms and progymnosperms. The vascular system of a majority of these plants resembles closely that of living conifers, being characterized, except in the most primitive forms which are protostelic, by a eustele consisting of axial sympodial bundles from which leaf traces diverge. The vascular supply to a leaf originates as a single trace with very few exceptions. It is proposed that the eustele in the gyrr.nosperms has evolved directly from the protostele by gradual medullation and concurrent separation of the peripheral conducting tissue into longitudinal sympodial bundles from which traces diverge radially. A subsequent modification results in divergence of traces in a tangential plane, The closed vascular system of conifers with opposite and whorled phyllotaxis, in which the vascular supply to a leaf originates as two traces which subsequently fuse, is considered to be derived from the open sympodial system characteristic of most gymnosperms. This hypothesis of stelar evolution is at variance with that of Jeffrey which suggests that the eustele of seed plants is derived by the lengthening and overlapping of leaf gaps in a siphonostele followed by further reduction in the resultant vascular bundles. This study suggests strongly that the "leaf gap" of conifers and other extant gymnosperms is not homologous with that of siphonostelic ferns and strengthens the validity of the view that Pterop­ sida is an unnatural group.
    [Show full text]
  • BOSTONIA PERPLEXA GEN. ET SP. NOV., a CALAMOPITYAN AXIS from the NEW ALBANY SHALE of Kentucky1
    Amer. J. Bot. 65(4): 459-465. 1978. BOSTONIA PERPLEXA GEN. ET SP. NOV., A CALAMOPITYAN AXIS FROM THE NEW ALBANY SHALE OF KENTUCKy1 WILLIAM E. STEIN, JR. AND CHARLES B. BECK Department of Botany. University of Michigan. Ann Arbor 48109 ABSTRACT Bostonia perplexa, gen. et sp. nov .. was collected from the Lower Mississippian Falling Run member of the Sanderson Formation. The single short segment of an axis. preserved as a petrifaction. contains at least three vascular columns. each with both primary and secondary tissues. Primary xylem is two or three ribbed. and contains several mesarch protoxylem strands. Gymnospermous secondary xylem is characterized by both uniseriate and multi seriate rays. The ground tissue is parenchymatous except for a few clusters of sclerotic cells. In its apparent polystelic nature. the specimen superficially resembles members of the Pennsylvanian to Permian Medullosaceae. All evi­ dence currently available. however. leads to the conclusion that this species should be placed in the Upper Devonian to Lower Mississippian Calamopityaceae. It has not been determined with certainty whether the species is polystelic (in the sense of the Medullosaceae), or whether the apparent polystely is the result of stelar branching proximal to the level of branch divergence. A SPECIMEN collected from the Falling Run among others. Reviews of the flora and stratig­ member of the Sanderson Formation and de­ raphy of the Devonian black shales were con­ scribed in this paper represents a new member tributed by Hoskins and Cross (195Ib) and Cross of the New Albany Shale flora. The vascular and Hoskins (1951). plant flora of the New Albany Shale is quite di­ As might be expected from its position in the verse, containing members from the Progymnos­ geologic column, the New Albany Shale flora permopsida, Lycopsida, Pteridospermales, Cla­ contains some elements typical of both the Up­ doxylales, and Coenopteridales.
    [Show full text]
  • Rev Palaeobot Paly 2006 142 AL
    Faironia difasciculata, a new gymnosperm from the Early Carboniferous (Mississippian) of Montagne Noire, France Anne-Laure Decombeix, Jean Galtier, Brigitte Meyer-Berthaud To cite this version: Anne-Laure Decombeix, Jean Galtier, Brigitte Meyer-Berthaud. Faironia difasciculata, a new gym- nosperm from the Early Carboniferous (Mississippian) of Montagne Noire, France. Review of Palaeob- otany and Palynology, Elsevier, 2006, 142 (3), pp.79-92. 10.1016/j.revpalbo.2006.03.020. hal- 00112100 HAL Id: hal-00112100 https://hal.archives-ouvertes.fr/hal-00112100 Submitted on 9 Nov 2006 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Faironia difasciculata , a new gymnosperm from the Early Carboniferous (Mississippian) of Montagne Noire, France. Anne-Laure Decombeix *, Jean Galtier and Brigitte Meyer-Berthaud Botanique et bioinformatique de l'architecture des plantes (UMR 5120 CNRS- CIRAD), TA40/PS2, CIRAD, Boulevard de la Lironde, 34398 Montpellier cedex 5, France Abstract A new taxon of probable gymnosperm affinities is described from the base of the Carboniferous (Mississippian, Middle Tournaisian) of Montagne Noire, southern France. It is based on a permineralised stem showing vascular and cortical tissues, and one attached petiole base. Faironia difasciculata gen.
    [Show full text]
  • (Revised with Costs), Petrified Forest National Park
    National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Natural Resource Condition Assessment Petrified Forest National Park (Revised with Costs) Natural Resource Report NPS/PEFO/NRR—2020/2186 The production of this document cost $ 112,132, including costs associated with data collection, processing, analysis, and subsequent authoring, editing, and publication. ON THE COVER Milky Way over Battleship Rock, Petrified Forest National Park Jacob Holgerson, NPS Natural Resource Condition Assessment Petrified Forest National Park (Revised with Costs) Natural Resource Report NPS/PEFO/NRR—2020/2186 J. Judson Wynne1 1 Department of Biological Sciences Merriam-Powell Center for Environmental Research Northern Arizona University Box 5640 Flagstaff, AZ 86011 November 2020 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a range of reports that address natural resource topics. These reports are of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate comprehensive information and analysis about natural resources and related topics concerning lands managed by the National Park Service. The series supports the advancement of science, informed decision-making, and the achievement of the National Park Service mission. The series also provides a forum for presenting more lengthy results that may not be accepted by publications with page limitations. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner.
    [Show full text]
  • Lyginopteris Royalii Sp. Nov. from the Upper Mississippian of North America
    Review of Palaeobotany and Palynology 116 (2001) 159±173 www.elsevier.com/locate/revpalbo Lyginopteris royalii sp. nov. from the Upper Mississippian of North America Alexandru Mihail Florian Tomescu*, Gar W. Rothwell, Gene Mapes Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA Received 22 August 2000; accepted for publication 6 February 2001 Abstract A new species of the seed fern Lyginopteris is described from a nodule in Upper Mississippian (middle Chesterian-Namurian A) shales of the Fayetteville Formation in northwestern Arkansas. The pyritized stem is 29 cm long and slightly compressed, with a diameter of about 11 £ 5 mm, and shows seven diverging leaf bases. The primary xylem of the specimen is eustelic. Foliar bundles extend through ®ve internodes before entering the rachis bases; they do not divide along their trajectory through the stem. Phyllotaxis of the specimen approaches 2/5. Longitudinally oriented sclerenchyma strands accompany the diverging foliar vascular bundles adaxially in the cortex, and are incorporated in the outer cortex above the level of foliar rachis divergence. In contrast to previously described Lyginopteris species, this species lacks capitate epidermal glands. A Lygino- pteris type rachis with a paired vascular bundle is preserved in the same nodule. Coprolites probably produced by oribatid mites are present in different tissues of the stem. The study of the leaf trace divergence necessitated the use of a deformation model to help reconstruct the original position of the cauline bundles in the compressed stele. This occurrence of Lyginopteris con®rms earlier reports of the genus from North America and emphasizes that it was not restricted to Western Europe.
    [Show full text]
  • MINUTES of the BOARD of ALDERMEN REGULAR MEETING of MARCH 21, 2017 Page I Of5
    MINUTES OF THE BOARD OF ALDERMEN REGULAR MEETING OF MARCH 21, 2017 Page I of5 1. CALL TO ORDER A regular meeting of the Board of Aldermen was convened at 7:00 p.m. on Tuesday, March 21, 2017, at City Hall located at 8880 Clark Avenue, Parkville, Missouri, and was called to order by Mayor Nanette K. Johnston. City Clerk Melissa McChesney called the roll as follows: Ward I Alderman Diane Driver - present Ward 1 Alderman Tina Welch - present Ward 2 Alderman Jim Werner - present Ward 2 Alderman Dave Rittman - present Ward 3 Alderman Robert Lock - present Ward 3 Alderman Douglas Wylie - absent with prior notice Ward 4 Alderman Marc Sportsman - present Ward 4 Alderman Greg Plumb - present A quorum of the Board of Aldermen was present. The following staff was also present: City Administrator Joe Parente Kevin Chrisman, Police Chief Alysen Abel, Public Works Director Stephen Lachky, Community Development Director Matthew Chapman, Finance/Human Resources Director Tim Blakeslee, Assistant to the City Administrator Chris Williams, City Attorney Mayor Johnston led the Board in the Pledge of Allegiance to the Flag of the United States of America. Mayor Johnston observed a moment of silence for Toni Anderson. 2. CITIZEN INPUT A. Park University Fossil Presentation Scott Hageman, Tim Northcutt, Patty Ryberg and Brian Hoffman from Park University presented information about a new fossil that was found by amateur paleontologist Tim Northcutt on university property. A handout was distributed during the meeting attached as Exhibit A. They stated that Parkvillia northcutti was considered to be a link between conifers and fems and the earliest evidence of seeds.
    [Show full text]
  • Pteridophytes, Gymnosperms and Paleobotany)
    PLANT DIVERSITY-II (PTERIDOPHYTES, GYMNOSPERMS AND PALEOBOTANY) UNIT I: PTERIDOPHYTES General characters, Reimer’s classification (1954). Telome concept. Sporangium development – Eusporangiate type and Leptosporangiate type. Apogamy, Apospory, Heterospory and Seed habit. Detailed account on stellar evolution. UNIT II: Brief account of the morphology, structure and reproduction of the major groups- Psilophytopsida, Psilotopsida, Lycopsida, Sphenopsida and Pteropsida. (Individual type stydy is not necessary). Economic importance of Gymnoperms. UNIT III: GYMNOSPERMS General characters – Classification of Gymnosperms (Sporne, 1965), Orgin and Phylogeny of Gymnosperms, Gymnosperms compared with Pteridophytes and Angiosperms- Economic Importance of Gymnosperms. UNIT IV: A general account of distribution, morphology, anatomy, reproduction and life cycle of the following major groups – Cycadopsida (Pteridospermales, Bennettitales, Pentaxylales, Cycadales) Coniferopsida (Cordaitales, Coniferales, Ginkgoales) and Gnetopsida (Gneales). UNIT V: PALEOBOTANY Concept of Paleobotany= Geological time scale- Fossil- Fossilization- Compressions, Incrustation, Casts, Molds, Petrifactions, Compactions and Caol balls. Detailed study of the fossil forms- Pteridophytes: Lepidodendron, Calamites. Gymnosperms: Lyginopteris, Cordaites. Role of fossil in oil exploration and coa excavation, Paleopaynology. Prepared by: Unit I and II 1. Dr. A.Pauline Fathima Mary, Guest Lecturer in Botany K. N. Govt. Arts College(W), Auto., Thanjavur. Unit III and IV 1. Dr. S.Gandhimathi, Guest Lecturer in Botany, K. N. Govt. Arts College(W), Auto., Thanjavur. Unit V: 1. Dr. G.Santhi, Head and Assistant professor of Botany, K. N. Govt. Arts College(W), Auto., Thanjavur. Reference: 1. Rashid, A, (2007), An Introduction to Peridophytes- Vikas Publications, New Delhi. 2. Sporne, K.R. (1975). The Morphology of Pteridophytes, London. 3. Coultar, J. M. and Chamberin, C, J. (1976). Morphology of Gymnosperms.
    [Show full text]
  • Download This Article As
    Int.J.Curr.Res.Aca.Rev.2017; 5(6): 49-55 International Journal of Current Research and Academic Review ISSN: 2347-3215 (Online) ҉҉ Volume 5 ҉҉ Number 6 (June-2017) Journal homepage: http://www.ijcrar.com doi: https://doi.org/10.20546/ijcrar.2017.506.007 Fossil Gymnosperms-A Review Teena Agrawal* and Priyanka Danai Banasthali University, Niwai, India *Corresponding author Abstract Article Info Gymnosperm are the plants which have fully exposed ovules not enclosed in the fruit, Accepted: 05 June 2017 they have the long evolutionary history. The palaeobotany of the gymnosperms goes Available Online: 20 June 2017 from the early Triassic to the late cretaceous. Gymnosperm is the most ancient seed plant that originated during the late paleozoic era and flourish well in the Mesozoic era. Keywords The long pathway of the evolution has a number of the lines of the cladistcs and the diverge lines of the evolution at that time a number of the plants of that lineage evolved Fossil gymnosperms, and other plants group extinct in the liens of the evolution. There are a large group of Evolution, the gymnosperms who have along linage of the fossil gymnosperms, in this series, Fossil gymnosperms, pteridopaermales, having lyginopteridaceae, medullasaceae, glsospteridaceae, Bennttitlaes, Caytoniales, calamopityaceae, bennettitales are the group having a very long and diverse kind of the Pteridopsermales, evolutionary history. However in that era majority f the gymnosperms’ are extinct, they Cladistices. are presented by only the cycadales and conifelraes, gnetlaes. Introduction a fossil history. In that review articles we are trying to analyse the fossil history of the gymnosperms.
    [Show full text]
  • Phenotypic Plasticity of the Hydrasperman Seed Fern <Italic
    Int. J. Plant Sci. 173(7):823–834. 2012. Ó 2012 by The University of Chicago. All rights reserved. 1058-5893/2012/17307-0008$15.00 DOI: 10.1086/666661 PHENOTYPIC PLASTICITY OF THE HYDRASPERMAN SEED FERN TETRASTICHIA BUPATIDES GORDON (LYGINOPTERIDACEAE) Michael T. Dunn1,* and Gar W. Rothwelly *Department of Biological Sciences, Cameron University, Lawton, Oklahoma 73505, U.S.A.; and yDepartment of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, U.S.A., and Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, U.S.A. Fifty-nine stems of Tetrastichia bupatides, numerous frond segments, and roots from Oxroad Bay, Scotland, have recently been analyzed. They reveal that many characters originally used to describe this species exhibit a wider range of variation than previously suspected. These data suggest that ribs of the protostele are most commonly four in number but range from three to five. Phyllotaxy ranges from opposite decussate to two- fifths, and rachis forking can be equal or unequal. Secondary xylem could be produced by all stems regardless of size, and rachis trace morphology ranges from ‘‘butterfly’’ shaped, to U-, to broadly U-, to T-shaped. Pinnules are vascularized by a single trace that diverges from the outermost protoxylem strand of a pinna trace. These ranges of variation for many characters complicate identification of isolated specimens, but stems can be identified by a consistent mode of rachis trace production, and frond parts can be correlated by common histological characters and a continuous range of variation in trace configuration. These wide ranges of variation in numerous characters demonstrate that phenotypic plasticity could be far greater in some hydrasperman seed ferns than previously realized and the taxonomic diversity at Oxroad Bay may be lower than previously thought.
    [Show full text]
  • Paleoecology of Late Paleozoic Pteridosperms from Tropical Euramerica^ William A
    Journal of the Toirey Botanical Society 133(1), 2006, pp. 83—118 Paleoecology of Late Paleozoic pteridosperms from tropical Euramerica^ William A. DiMichele^ ^ Department of Paleobiology, NMNH Smithsonian Institution, Wasliington, DC 20560 Tom L. Phillips Department of Plant Biology, University of Illinois, Urbana, IL 61801 Hermann W. Pfefferkorn Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19106 DiMlCHELE, W. A. (Department of Paleobiology, NMNH, Smithsonian Institution, Washington, DC 20560), T. L. PHILLIPS (Department of Plant Biology, University of Illinois, Urbana, IL 61801), AND H. W. PFEFFERKORN (Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19106). Paleo- ecology of Late Paleozoic pteridosperms from tropical Euramerica. J. Torrey Bot. Soc. 133: 83—118. 2006.— Late Paleozoic pteridosperms are a paraphyletic group of seed plants that were prominent elements of tropical ecosystems, primarily those of wetlands or the wetter portions of seasonally dry environments. Because the group is more a tradition-based, historical construct than a well circumscribed phylogenetic lineage, the wide variance in ecological roles and ecomorphological attributes should not be surprising. Pteridosperms can be the dominant canopy trees in local habitats, prominent understory trees, scrambling ground cover, thicket-formers, or liana-like plants and vines. Some species appear to have been weedy opportunists, although this ecological strategy seems to be a minor part of the wide spectrum of pteridosperm life habits. Most pteridosperms appear to have preferred wetter parts of the landscape, though not standing water, and relatively nutrient-rich settings (in comparison with groups such as tree ferns or lycopsids). Of the Paleozoic pteridosperms as traditionally circumscribed, only the peltasperms survived to become major elements in the Mesozoic.
    [Show full text]
  • A Middle Pennsylvanian Macrofloral
    Journal of Paleontology, 90(4), 2016, p. 589–631 Copyright © 2016, The Paleontological Society 0022-3360/16/0088-0906 doi: 10.1017/jpa.2015.69 A Middle Pennsylvanian macrofloral assemblage from wetland deposits in Indiana (Illinois Basin): a taxonomic contribution with biostratigraphic, paleobiogeographic, and paleoecologic implications Arden R. Bashforth,1* William A. DiMichele,1 Cortland F. Eble,2 and W. John Nelson3 1Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA 〈[email protected]〉; 〈[email protected]〉 2Kentucky Geological Survey, University of Kentucky, Lexington, KY 40560, USA 〈[email protected]〉 3Illinois State Geological Survey, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA 〈[email protected]〉 Abstract.—Taxonomic analysis is provided for a Middle Pennsylvanian macrofloral assemblage collected from clastic wetland deposits in Clay County, Indiana, on the eastern margin of the Illinois Basin. Adpressed plant fossils were recovered from four distinct beds in the lowermost Staunton Formation, positioned above the Minshall Coal (uppermost Brazil Formation), part of a succession deposited near the Atokan-Desmoinesian boundary. The assemblage of 22 fossil-taxa is dominated by pteridosperms (including Neuropteris flexuosa, Macroneuropteris scheuchzeri, Alethopteris densinervosa, Neuropteris ovata, Eusphenopteris neuropteroides, and Neuropteris missouriensis) with lesser cordaitaleans (Cordaites spp. indet.) and sphenopsids (particularly Sphenophyllum cuneifo-
    [Show full text]
  • Botanical Nomenclature and Plant Fossils
    TAXON 59 (1) • February 2010: 261–268 Cleal & Thomas • Botanical nomenclature and plant fossils NOMENCLATURE Edited by John McNeill, Anthony E. Orchard & John C. David Botanical nomenclature and plant fossils Christopher J. Cleal1 & Barry A. Thomas2 1 Department of Biodiversity & Systematic Biology, Amgueddfa Cymru – National Museum Wales, Cardiff CF10 3NP, U.K. 2 Institute of Biological, Environmental and Rural Sciences, University of Aberystwyth, Llanbadarn Fawr, Aberystwyth SY23 3AL, U.K. Author for correspondence: Christopher J. Cleal, [email protected] Abstract The provisions in the Code for naming plant fossil taxa have changed substantially over the years. The history of these changes reflects the tension between palaeobotanists (including palynologists studying plant microfossils) who need a flexible set of regulations, and the tendency for the Code to include nomenclatural regulations that constrain taxonomic decisions. The current Vienna Code now provides for plant fossils to be named as fossil taxa, which is a flexible taxonomic concept that should suit the needs of most palaeobotanists. However, the Vienna Code also incorporates the more restrictive concept of morphotaxa and most palaeobotanists seem to be under the misapprehension that plant fossils can only be named as morphotaxa. In our view, the concept of morphotaxa is logically flawed and unnecessary in practice, and should be removed from the Code. Keywords form-genera; fossil taxa; morphotaxa; organ-genera; palaeobotany; palynology; satellite taxa INTRODUCTION at least partly lost through fossilisation. They are now biologi- cally inert objects, but originated from living organisms. Since the publication of the Vienna Rules (Briquet, 1906) Fossil plants, in contrast, were the plants from which these it has been accepted that taxonomic nomenclature of plant fossilised remains were derived.
    [Show full text]