Probable Fertile Region of Asteroxylon mackiei K. and L.

Lyon, A. G.

doi:10.1038/2031082b0

Cited by 47 publications

(28 citation statements)

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“…Each strand became spindle-shaped below the sporangium before fanning out into a kind of transfusion tissue at its base. The apex of stalk formed a small pad of tissue in the bottom of the sporangial cavity (Lyon 1964;Bhutta 1969). The most detailed and accurate reconstructions of fertile shoots are in Bhutta's (1969) thesis.…”

Section: Asteroxylon Mackieimentioning

confidence: 99%

Embryophytic sporophytes in the Rhynie and Windyfield cherts

Edwards

2003

Transactions of the Royal Society of Edinburgh: Earth Sciences

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Brief descriptions and comments on relationships are given for the seven embryophytic sporophytes in the cherts at Rhynie, Aberdeenshire, Scotland. They are Rhynia gwynnevaughanii Kidston & Lang, Aglaophyton major D. S. Edwards, Horneophyton lignieri Barghoorn & Darrah, Asteroxylon mackiei Kidston & Lang, Nothia aphylla Lyon ex Høeg, Trichopherophyton teuchansii Lyon & Edwards and Ventarura lyonii Powell, Edwards & Trewin. The superb preservation of the silica permineralisations produced in the hot spring environment provides remarkable insights into the anatomy of early land plants which are not available from compression fossils and other modes of permineralisation. They include soft tissues, such as those surrounding stomata, rhizoids, apical and lateral meristems, and diversity in conducting cells, with inferences for palaeoecophysiology, including water use efficiency, transport and absorption, and for growth processes and patterns.

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Section: Asteroxylon Mackieimentioning

confidence: 99%

Embryophytic sporophytes in the Rhynie and Windyfield cherts

Edwards

2003

Transactions of the Royal Society of Edinburgh: Earth Sciences

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“…gc, d ) (D. S. Edwards, 1986)~ Horneophyton (Hornea) lignieri (Fig. 5a, b) (Barghoorn & Darrah, 1938) and Asteroxylon mackiei (Lyon, 1964). Only two new sporophytes have been described from the Rhynie Chert in the last 70 years : Nothia aphylla (El-Saadawy & Lacey, I 979 a) and Trichopherophyton teuchansii (Lyon & Edwards, 1991).…”

Section: ( a ) The Sporophyte Generationmentioning

confidence: 99%

“…Recent work has verified the original concept of the Rhynie Chert plants as simple sporophytes but has also shown that certain important features of these original reconstructions are inaccurate or poorly supported. The original problematic reconstruction of the early lycopod Asteroxylon mackiei was based on the association of two separate plants (Lyon, 1964; Lacey, 1 9 7 9~) .…”

Section: ( a ) The Sporophyte Generationmentioning

confidence: 99%

Alternation of Generations in Land Plants: New Phylogenetic and Palaeobotanical Evidence

Kenrick

1994

Biological Reviews

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Summary Current ideas on the evolution of alternation of generations in land plants are reviewed in the context of important recent advances in plant systematics and the discovery of remarkable new palaeobotanical evidence on early embryophyte life cycles. An overview of relationships in major groups of green plants is presented together with a brief review of the early fossil record as a prelude to discussing hypotheses of life cycle evolution. Recent discoveries of life cycles in the early fossil record are described and assessed. The newly discovered gametophyte and sporophyte associations are based on exceptionally well‐preserved material from the Rhynie Chert, Scotland (Middle Devonian: 380–408 Myr) and compression fossils from other Devonian localities. These data document diplobiontic life cycles in plants at the ‘protracheophyte’ and early tracheophyte level of organization. Furthermore, the early fossils have a more or less isomorphic alternation of generations, a striking departure from life cycles in extant embryophytes. This unexpected similarity between gametophyte and sporophyte calls for a cautious approach in identifying ploidy level in early groups. Viewed in a systematic context, the neontological and palaeontological data contribute towards the formulation of a coherent hypothesis of life cycle evolution in major, early embryophyte groups. Evidence from extant groups strongly supports a single direct origin of the diplobiontic life cycles of land plants from haploid, haplobiontic life cycles in ancestral ‘charophycean algae’. The interest of the new palaeobotanical data lies in its relevance to life cycle evolution at the restricted level of vascular plants rather than at the more general level of embryophytes (vascular plants plus ‘bryophytes’). The occurrence of morphologically complex, axial gametophytes in early vascular plants is consistent with the moss sister‐group proposed in some cladistic analyses. Similarities of moss gametophytes to fossils in the vascular plant stem‐group are discussed, and it is argued that the late appearance of mosses in the macrofossil record may be due to the problem of recognizing stem‐group taxa. The new palaeobotanical evidence conflicts with previous hypotheses based on extant groups that interpret morphological simplicity as the plesiomorphic condition in the gametophytes of vascular plants. These new data indicate that a significant elaboration of both gametophyte and sporophyte occurred early in the tracheophyte lineage, and that the gametophytes of extant ‘pteridophytes’ are highly reduced compared to those of some of the earliest ‘protracheophytes’. Vestiges of this early morphological complexity may remain in the gametophytes of some extant groups such as Lycopodiaceae.

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“…Kidston & Lang has now been shown (Lyon, 1964;Hoeg, 1967a) to have sporangia which are borne directly on the main axes in amongst the veinless 'microphyll' leaves (Pl. 2, fig.…”

Section: Asteroxylon Mackieimentioning

confidence: 99%

“…(4) The Siegenian (390-374 million years ago) In floras of Siegenian age we have evidence of much greater diversity of morphology and in a number of cases, knowledge of internal anatomy from petrified material (e.g. Kidston & Lang, 1917, 1920Lyon, 1964;Edwards, 1968). There is clear evidence of pronounced overtopping of one arm of a dichotomy by a larger and subsequently thicker axis (as seen in a number of Siegenian genera, e.g.…”

Section: Major Events Of T H E First 30 Million Years O F Plant Life mentioning

confidence: 99%

The Rise of the First Land Plants

Chaloner

1970

Biological Reviews

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Probable Fertile Region of Asteroxylon mackiei K. and L.

Cited by 47 publications

References 1 publication

Embryophytic sporophytes in the Rhynie and Windyfield cherts

Embryophytic sporophytes in the Rhynie and Windyfield cherts

Alternation of Generations in Land Plants: New Phylogenetic and Palaeobotanical Evidence

The Rise of the First Land Plants

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