Runcaria, a Middle Devonian Seed Plant Precursor
P. Gerrienne,1*
B. Meyer-Berthaud,2
M. Fairon-Demaret,1
M. Streel,1
P. Steemans1
The emergence of the seed habit in the Middle Paleozoic was a decisive evolutionary breakthrough. Today, seed plants are the most successful plant lineage, with more than 250,000 living species. We have identified a middle Givetian (385 million years ago) seed precursor from Belgium predating the earliest seeds by about 20 million years. Runcaria is a small, radially symmetrical, integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the multilobed integument. This extension is assumed to be involved in anemophilous pollination. Runcaria sheds new light on the sequence of character acquisition leading to the seed.
1 Département de Géologie, B18, Université de Liège, Sart Tilman, Liège 1, Belgique.
2 Botanique et Bioinformatique de l'Architecture des Plantes, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, TA40/PS2, Boulevard de la Lironde, 34398 Montpellier Cedex 5, France.
* To whom correspondence should be addressed. E-mail: p.gerrienne{at}ulg.ac.be
