Floral Ontogeny in Ficinia and Isolepis (Cyperaceae), with Focus on the Nature and Origin of the Gynophore

• Published in: Annals of Botany
• Main Authors: VRIJDAGHS, A., GOETGHEBEUR, P., MUASYA, A. M., CARIS, P., SMETS, E.
• Format: Text
• Language: English
• Published: Oxford University Press 2005
• Subjects: ORIGINAL ARTICLES; Antarc*; Antarctica
• Online Access: http://aob.oxfordjournals.org/cgi/content/short/96/7/1247; https://doi.org/10.1093/aob/mci276

• 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.