Plant Biol (Stuttg) 2003; 5(3): 297-310
DOI: 10.1055/s-2003-40791
Original Paper

Georg Thieme Verlag Stuttgart · New York

Morphogenesis of Male Sporangiophores of Zamia amblyphyllidia D. W. Stev.

M. Mundry 1 , T. Stützel 1
  • 1Ruhr-Universität Bochum, Lehrstuhl für Spezielle Botanik, Bochum, Germany
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Publication History

Publication Date:
22 July 2003 (online)

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Abstract

Morphology, development and anatomy of the male cones of Zamia amblyphyllidia are studied here to amass additional information to develop a more convincing concept of the evolution of seed plants. The male sporangiophores of the cycads are usually regarded as simple sporangiophores with synangia on the abaxial side. Our developmental study of the male sporangiophores of Zamia amblyphyllidia, by scanning and light microscopy, suggests that the sporangiophores are pinnate, with synangia on reduced leaflets. This indicates that a significant difference between female and male sporangiophores in cycads, as previously stated, does not exist. Comparisons of male sporangiophores of cycads with those of conifers show that they are not homologous. Rather, the synangia of the cycads may better be homologised with the radial synangia groups in some pteridosperm taxa. Although several authors assume that the cycad precursor displayed entire, fertile and sterile leaves, our interpretations of the male sporangiophores indicate that cycads originated from a pinnate pteridospermous ancestor with radial synangia groups. These hypotheses may point to the Medullosaceae, although this remains to be substantiated.

References

M. Mundry

Ruhr-Universität Bochum
Spezielle Botanik

NDEF 05/776

44780 Bochum

Germany

Email: marcus.mundry@ruhr-uni-bochum.de

Section Editor: G. Gottsberger