Novel conducting tissues in Lower Devonian plants

Edwards, Dianne; Axe, Lindsey

doi:10.1111/j.1095-8339.2000.tb02359.x

Cited by 13 publications

(15 citation statements)

References 29 publications

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“…Micropitted wall lines the lumen; further outgrowths into the lumen are very rare. Two further specimens have been found that contain a central strand in which cells show the same kind of pitting we recorded in an earlier account (Edwards & Axe, 2000), where the perforated layer lines the lumen. A branching example (2.1 mm long) is filled with pyrite, but with a distinct central strand (Figs 97,98).…”

Section: Functionssupporting

confidence: 76%

“…Details of the stream-side Lochkovian locality in the Ditton Series to the north of Brown Clee Hill in Shropshire and techniques involved in preparing the 3dimensionally preserved coalified axes (mesofossils) for SEM are given in Edwards & Axe (2000). The majority of coalified fragments isolated from this locality are compressed and show little cellular detail.…”

Section: Methodsmentioning

confidence: 99%

“…Anatomical screening of tiny sterile coalified axial fossils (mesofossils) from a Lower Devonian (Lochkovian) locality in the Welsh Borderland has revealed remarkable structural variations in the architecture of centrally placed, elongate presumed conducting elements (Edwards, 1999(Edwards, , 2000Edwards & Axe, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Diversity in conducting cells in early land plants and comparisons with extant bryophytes

Edwards

Axe

Duckett

2003

Botanical Journal of the Linnean Society

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Anatomical screening using scanning electron microscopy (SEM) of short lengths of smooth coalified axes (mesofossils) from a Lochkovian (Lower Devonian) locality in the Welsh Borderland, Shropshire has revealed extensive diversity in the architecture of centrally aggregated, elongate cells. At least 14 types have been discovered, each distinguished by variation in wall architecture and combination of the cells in the central strand. End walls have not been seen. These elongate cells may have smooth, uniformly thick or thin walls, walls with smooth projections either traversing or lining the lumen, or bilayered walls, the innermost perforated by pores of plasmodesmata dimensions. The latter type may be further divided on presence or absence of projections which may line the lumen, but usually cross it and are highly disorganized. Indeed, none of the cells shows the regularity associated with the secondary thickenings of tracheids, but the imperforate/pitted forms with projections superficially resemble the S-type tracheids of the Rhyniopsida in basic construction. Simply pitted types show greater similarity with the waterconducting cells (WCCs) of liverworts and Takakia . To facilitate direct comparison with bryophyte conducting elements, SEM studies were undertaken on the WCCs of a number of mosses and liverworts and on the leptoids of mosses, in conjunction with a range of degradation experiments designed to assess the fossilization potential of these cells. With the exception of polytrichaceous hydroids, the latter demonstrated the resilience of hydroids and leptoids to the chemical treatments. In addition, dehydration of the leptoids produced globular residues similar to those seen in some of the fossils. This combination of techniques raises the possibility that food-conducting cells might well be preserved in coalified fossils, and hence extends the interpretation of the functions of the elongate cells. Broadly speaking, imperforate bilayered examples may have been involved in water conduction, cells with globular residues with or without pitting involved in metabolite movement, and smooth walled examples with or without projections involved in support. The wider affinities of the plants which produced the axes remain equivocal and in the absence of sporangia it is impossible to assign them to a genus. However, this anatomical diversity in vegetative remains of extreme simplicity demonstrates far greater diversity in early land vegetation than is apparent from perusal of species lists. Figures 7-12. NMW99.20G.5 continued. Scale bars = 1 µ m. Figs 7,8. LS and oblique TS of micropitted elements with horizontal ridging. Note part of element with smooth projections to top of 7. Fig. 9. TS smooth walled element lacking projections. Figs 10,11. Fractured junctions between two types of element with projections. Arrow = smooth walled cell lacking projections. Fig. 12. Fragments of perforated wall layers. 302 D. EDWARDS ET AL .

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Section: Functionssupporting

confidence: 76%

Section: Methodsmentioning

confidence: 99%

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Diversity in conducting cells in early land plants and comparisons with extant bryophytes

Edwards

Axe

Duckett

2003

Botanical Journal of the Linnean Society

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“…As a consequence, various groups of Devonian plants are difficult to assign unequivocally to either the bryophytes or the vascular plants on the basis of their preserved morphological traits (Edwards & al. 1995;Edwards & Axe, 2000).…”

Section: Introductionmentioning

confidence: 99%

Paraphyly of bryophytes and close relationship of hornworts and vascular plants inferred from chloroplast rDNA spacers sequence analysis

Samigullin

Yacentyuk

Degtyaryeva

et al. 2002

Arctoa, a jornal of bryology

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Phylogenetic analysis of nucleotide sequences of chloroplast rDNA internal transcribed spacer (cpITS) regions (cpITS2-4) of 14 species of liverworts, 4 species of hornworts, 20 species of mosses, 7 species of lycopods and 2 species of algae was carried out. Phylogenetic trees constructed by maximum parsimony, maximum likelihood and neighbour-joining methods indicated that bryophytes are not monophyletic. The cpITS data suggest that the hepatic lineage branches most deeply in the land plant topology and that mosses are monophyletic, forming the sister group of lycopods and hornworts. Within the mosses, a conspicuous deletion with distinct phylogenetic distribution was observed in the cpITS3 region. This deletion is absent in other land plants, including the enigmatic genus Takakia, and marks Takakia as an evolutionary lineage distinct from mosses. ÐåçþìåÏðîâåäåí ôèëîãåíåòè÷åñêèé àíàëèç íóêëåîòèäíûõ ïîñëåäîâàòåëüíîñòåé ñïåéñåðîâ õëîðîïëàñòíîé ðÄÍÊ (cpITS2-4) ó 14 âèäîâ ïå÷åíî÷íèêîâ, 4 âèäîâ àíòîöåðîòîâûõ, 20 âèäîâ ìõîâ, 7 âèäîâ ïëàóíîâèäíûõ è 2 âèäîâ õàðîâûõ âîäîðîñëåé. Ñîãëàñíî òîïîëîãèè ôèëîãåíåòè÷åñêèõ äåðåâüåâ, ðåêîíñòðóèðîâàííûõ ìåòîäàìè ìàêñèìàëüíîãî ïðàâäî-ïîäîáèÿ, áëèaeàéøåãî ñâÿçûâàíèÿ è ìàêñèìàëüíîé ýêîíîìèè, ìîõîîáðàçíûå íå ìîíîôèëåòè÷íû. Íà êëàäîãðàììàõ ñðåäè íàçåìíûõ ðàñòåíèé ïåðâûìè îòäåëÿþòñÿ âåòâè, âåäóùèå ê ïå÷åíî÷íèêàì. Ìõè ïðåäñòàþò êàê ìîíîôèëåòè÷åñêàÿ ãðóïïà, ñåñòðèíñêàÿ ê êëàäå, îáúåäèíÿþùåé ïëàóíîâèäíûå è àíòîöåðîòîâûå. Â íóêëåîòèäíîé ïîñëåäî-âàòåëüíîñòè cpITS3 ó ìõîâ îáíàðóaeåíà ïðîòÿaeåííàÿ äåëåöèÿ, îòñóòñòâóþùàÿ ó îñòàëüíûõ íàçåìíûõ ðàñòåíèé, âêëþ÷àÿ Takakia.

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“…These axial fossils rarely reach a length of 1 cm and are termed mesofossils (Edwards 1996). They reveal cellular detail of surfaces, including stomata on axes and sporangia (Edwards et al 1992(Edwards et al , 1998; Figure 4 m-q), of conducting cells (Edwards et al 1992Edwards and Axe 2000) and of in situ spores (Edwards 1996;Edwards and Richardson 2000; Figure 4 m-q). Some of the cigar-shaped spore masses are interpreted as coprolites, and provide evidence for plant-animal interaction, the latter probably myriapods (millipedes and euarthropleurids) as detritivory (Edwards et al 1995c).…”

Section: Mesofossils (Figure 4a-i)mentioning

confidence: 99%

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

Edwards

Richardson

2004

Geological Journal

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A comprehensive survey of plant assemblages from Upper Silurian (Gorstian-Pȓídolí) and Lower Devonian (LochkovianPragian) localities in South Wales and the Welsh Borderland is presented, together with some comments on recent improvements in dating and correlation. Spore assemblages provide a stratigraphic framework for plant evolutionary studies and, along with microvertebrates, enable correlation from continental to marine rocks, i.e. near-shore to shelf deposits. While it is recognized that the assemblages provide the most complete and extensive record of the history of vascular plants in a restricted geographical area during the time interval, it seems likely that major evolutionary innovation occurred elsewhere. The plants themselves display a number of types of fossilization. Particularly important are the pyrite permineralizations which have helped in the elucidation of the ultrastructure of tracheids in early vascular plants. Minute, coalified, relatively uncompressed fossils (mesofossils) from the Pȓídolí Lochkovian of the Welsh Borderland are hypothesized to be the products of wildfire, the earliest records to date. In addition to displaying often exquisite anatomical detail, the sporangia contain spores which have been linked to those in dispersed assemblages. Such relationships are helpful in the reconstruction of local and regional vegetation, even in the absence of meso-and megafossils. However, because these fossils are allochthonous and preserved in fluvial sediments, the habitats of the plants remain uncertain. A new hypothesis suggests that interfluvial areas, where calcretes are interpreted as relicts of vertisols and a seasonally dry climate, provided refugia in the Lower Devonian for the cryptosporeproducing plants which dominated Ordovician and Lower Silurian land vegetation, while vascular plants colonized areas in the immediate vicinity of rivers. Variation in regional vegetation is explored via comparisons of composition of spore assemblages in southern Britain and Scotland and timing of appearances of derived taxa, integrated with limited information on the spore producers.

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Novel conducting tissues in Lower Devonian plants

Cited by 13 publications

References 29 publications

Diversity in conducting cells in early land plants and comparisons with extant bryophytes

Diversity in conducting cells in early land plants and comparisons with extant bryophytes

Paraphyly of bryophytes and close relationship of hornworts and vascular plants inferred from chloroplast rDNA spacers sequence analysis

Silurian and Lower Devonian plant assemblages from the Anglo‐Welsh Basin: a palaeobotanical and palynological synthesis

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