II.—On the Structure of <i>Calymmatotheca kidstoni</i> Calder (emended) and <i>Genomosperma latens</i> gen. et sp. nov. from the Calciferous Sandstone Series of Berwickshire

Long, A. R.

doi:10.1017/s008045680010002x

Cited by 62 publications

(55 citation statements)

References 6 publications

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“…Early fossil seeds are usually supplied by a central terete xylem surrounded by delicate cells or cavity (decayed phloem?) [ Genomosperma kidstoni in Plate I, Figures eight (Long 41960a); Lyrasperma scotica in Plate II, Figure twenty three (Long 1960b); Dolichosperma sexangulatum in Plate IV, Figure fifty six (Long 1961); Elkinsia polymorpha in Figure fourty four (Rothwell et al 1989); Ruxtonia minuta in Plate 3, Figure 2 and Text-Figure 5f (Galtier et al 2007); Cardiocarpus samaratus in Figure twelve c (Wang et al 2003)] and they are terminal on shoots. Similar configuration has also been seen in the placental bundle in an anatomically preserved angiosperm, Beardia (Juglandaceae), from the Eocene of Canada (igures five, seven, eight of Elliott et al F2006).…”

Section: Discussionmentioning

confidence: 99%

From leaf and branch into a flower: Magnolia tells the story

2014

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BackgroundIn the classical doctrines, Magnolia was frequently considered the archetype among flowering plants, and its conduplicate carpel with marginal placentation was assumed to be derived from a leaf-like organ bearing ovules along its margins. Although the robustness of this concept has been seriously questioned by advances in botanical research, especially the emergence of Magnolia deeper in the angiosperm tree of life in molecular systematics, it remains the most-taught interpretation for the origin of carpels.ResultsTo test the validity of this classical doctrine, we performed comparative anatomical analyses of the vascular bundles in the flowers of Magnolia using fine (8-μm) paraffin -sections. We document the presence of two independent vascular systems in the carpels: the collateral bundles of the dorsal and ventral veins arising from the stelar bundle, and the amphicribral ovular bundles arising from the cortical bundles. This observation in conjunction with data from other fields concurrently suggests that the ovary wall is equivalent to a foliar organ whereas the placenta represents an ovule-bearing shoot.ConclusionsOur observation on the former model plant, Magnolia, nullifies the classical doctrine of carpel evolution and supports the Unifying Theory. This conclusion prompts a reconsideration of the concept of angiosperm flower evolution.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-55-28) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

From leaf and branch into a flower: Magnolia tells the story

2014

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“…Based on what could be seen in her ground thin sections, they did not seem to differ substantially from ovules that were known from the Late Carboniferous coal-balls. It was not until Long (1959Long ( , 1960 obtained fresh examples and applied the Joy et al (1956) modification of Walton's peel technique which Calder helped pioneer, that the true significance of this material was realized. Long showed that these primitive ovules, which he renamed Genomosperma kidstonii (Calder) Long and Lyrasperma scotica (Calder) Long, were substantially different from their Late Carboniferous counterparts: they lacked a micropyle, pollen capture instead being facilitated by an apical elongation of the nucellus, known as a lagenostome or salpinx.…”

Section: Marymentioning

confidence: 99%

The contribution of British women to Carboniferous palaeobotany during the first half of the 20th century

Fraser

Cleal

2007

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During the first half of the 20th century, over a third of British palaeobotanists working on Carboniferous plants were women; neither before nor after this period have women played such a prominent role in this field. Few of these women were able to develop significant careers within the subject. They nevertheless produced some of the most innovative work in the field, pioneering work in plant phylogeny, cuticle studies, biostratigraphy, morphological variation, and anatomical thin sectioning. Two factors were critical for allowing this work to develop: the support of a small number of male colleagues, notably F.

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“…In certain Devonian and Lower Carboniferous seed ferns (e.g., Genomosperrna, Long, 1959) the integument is deeply divided into several lobes and does not circumscribe a distinct micropyle. This condition is interpreted as primitive, based on the view that the integument probably evolved by fusion of sterile "telomes" surrounding a megasporangium (Andrews, 1963).…”

Section: Micropylementioning

confidence: 99%

Phylogenetic Relationships in Seed Plants

Crane

1985

Cladistics

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Abstract— The phylogenetic relationships of nineteen extant and fossil seed plants are considered. Analysis of 31 characters produced ten topologically similar and equally parsimonious cladograms. A strict consensus tree derived from these cladograms places Lyginopteris as the sister taxon to the other seed plants included. Within this clade all the taxa considered, except medullosans and cycads, form a single monophyletic group defined by the presence of flattened seeds and saccate pollen (“platy‐sperms”). Relationships between medullosans, cycads, and “platysperms” were not resolved, but within the “platysperm” clade conifers and cordaites (Cordaixylon, Mesoxylon) + Ginkgo form a monophyletic group (“coniferophytes”). The “higher platysperms” (glossopterids, Caytonia, corystosperms, Bennettitales, Pentoxylon, Gnetales, and angiosperms) are also monophyletic, but their relationship to “coniferophytes,” peltasperms, and Callistophyton is unresolved. Pentoxylon is placed as sister taxon to the Bennettitales, and together they form the sister group to a clade in which Gnetales and angiosperm are sister taxa. The Bennettitales + Pentoxylon + Gnetales + angiosperms (“anthophytes”) form a monophyletic sister group to the corystosperms. This analysis is compared with current classifications of seed plants. It does not support a close relationship between Bennettitales and cycads, it provides no evidence for seed plant polyphyly, and it strongly suggests that the current concept of seed ferns has little value in a phylogenetic context.

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II.—On the Structure of Calymmatotheca kidstoni Calder (emended) and Genomosperma latens gen. et sp. nov. from the Calciferous Sandstone Series of Berwickshire

Cited by 62 publications

References 6 publications

From leaf and branch into a flower: Magnolia tells the story

From leaf and branch into a flower: Magnolia tells the story

The contribution of British women to Carboniferous palaeobotany during the first half of the 20th century

Phylogenetic Relationships in Seed Plants

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