Skip Navigation

This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Content Snapshot
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (10)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by DUCKETT, J. G.
Right arrow Articles by LIGRONE, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by DUCKETT, J. G.
Right arrow Articles by LIGRONE, R.
Agricola
Right arrow Articles by DUCKETT, J. G.
Right arrow Articles by LIGRONE, R.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Annals of Botany 92: 513-521, 2003
© 2003 Annals of Botany Company

The Structure and Development of Haustorial Placentas in Leptosporangiate Ferns Provide a Clear-cut Distinction Between Euphyllophytes and Lycophytes

JEFFREY G. DUCKETT*,1 and ROBERTO LIGRONE2

1 School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK and 2 Dipartimento di Scienze Ambientali, Seconda Università di Napoli, via Vivaldi 43; I-81100 Caserta, Italy

* For correspondence. E-mail j.g.duckett{at}qmul.ac.uk

Received: 26 March 2003; Returned for revision: 21 May 2003; Accepted: 10 June 2003

This light and electron microscope study revealed that leptosporangiate ferns have highly distinctive gametophyte–sporophyte junctions characterized by sporophytic haustoria, the absence of intraplacental spaces and degenerating cells, and the early appearance of wall ingrowths in both generations. Other notable cytological features are highly pleomorphic plastids and mitochondrial aggregates in the gametophytic placental cells. Close similarities with the gametophyte–sporophyte junctions in Tmesipteris and major differences from those of homosporous lycophytes are in line with the placement of psilophytes and ferns in the same clade and distance both from lycophytes. A smooth interface between the two generations in Azolla suggests a clear-cut discontinuity between homosporous and heterosporous ferns, although this is the only heterosporous fern investigated to date. Similarities between the gametophyte–sporophyte junctions of leptosporangiate ferns and hornworts, when balanced against differences between them, are considered more likely the result of parallel evolution rather than homology.

Key words: Pteridophyte phylogeny, transfer cells, leptosporangiate ferns, Azolla, plastid ontogeny.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.