AOBPreview originally published online on October 10, 2005
Annals of Botany 2005 96(7):1247-1264; doi:10.1093/aob/mci276
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Floral Ontogeny in Ficinia and Isolepis (Cyperaceae), with Focus on the Nature and Origin of the Gynophore
1 Laboratory of Plant Systematics, Institute of Botany and Microbiology, K.U. Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium, 2 Research Group Spermatophytes, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium and 3 The East African Herbarium, National Museums of Kenya, PO Box 45166, Nairobi 00100, Kenya
* For correspondence. E-mail alexander.vrijdaghs{at}bio.kuleuven.be
Received: 3 May 2005 Returned for revision: 21 June 2005 Accepted: 29 August 2005 Published electronically: 10 October 2005
• Background and Aims The generic delimitations of Ficinia and Isolepis, sister genera in the Cypereae, are blurred. Typical Ficinia flowers have a lobed gynophore, which envelops the base of the nutlet, whereas in Isolepis the character is considered to be absent. Some former species of Isolepis, lacking the gynophore, were recently included in Ficinia. The floral ontogeny of representative taxa in Ficinia and Isolepis were investigated with the aim of evaluating the origin and nature of the gynophore in the Cypereae.
• Methods The spikelet and floral ontogeny in inflorescences collected in the field was investigated using scanning electron microscopy (SEM) and light microscopy (LM).
• Key Results SEM images of Isolepis setacea and I. antarctica, Ficinia brevifolia, F. minutiflora, F. zeyheri and F. gracilis, and LM sections of F. radiata, show that the gynoecium in Ficinia is elevated above the flower receptacle by the development of a hypogynous stalk. From its apex, a (often three-)lobed cup is formed, which envelopes the basal part of the later nutlet. In developing flowers of I. antarctica, a rudimentary hypogynous stalk appears. In I. setacea, rudiments of a hypogynous stalk can be observed at maturity. In F. radiata and F. zeyheri, intralocular hairs are present in the micropylar zone. At the surface of developing gynoecia in flowers of F. gracilis, star-shaped cuticular structures appear which disappear again at maturity.
• Conclusions The overall floral ontogeny of all species studied occurs following a typical scirpoid pattern, though no perianth primordia are formed. The gynophore in Ficinia originates as a hypogynous stalk, from which the typical gynophore lobes develop. The gynophore is not homologous with the perianth.
Key words: Ficinia, floral ontogeny, gynophore, Isolepis, scanning electron microscopy
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