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Keywords:

  • Bryophyta;
  • hydroids;
  • leptoids;
  • Rhyniophytina;
  • Tracheophyta

EDWARDS, D. S., 1986. Aglaophyton major, a non-vascular land-plant from the Devonian Rhynie Chert. The genus Aglaophyton is described to accommodate the plant formerly known as Rhynia major, re-examined using new material and techniques. The plant, which is a sporophyte, is suggested to have been shorter than originally supposed and to have formed extensive stands of decumbent axes. These features, with information on the angle of dichotomous branching and the frequency of sporangia, are incorporated into a new reconstruction of the plant. The conducting strand within the axes consists of three zones, a central region of thin-walled cells, a middle region of thick-walled cells and an outer region of thin-walled cells. There is no indication of differential wall thickenings in the cells of any of these zones and the strand is interpreted in terms of a bryophytic conducting strand, the inner two regions being comparable to hydroids and the outer region comparable to the leptoids found in polytrichaceous moss gametophytes and sporophyles. The plant thus exhibits characters intermediate between tracheophytes and some mosses and cannot be considered a member of either group; at the present time it is not assigned to a higher category. A rediagnosis of Rhynia gwynne-vaughanii, based on published results and new data, is also included.