title: Floral development in the tribe Cedreleae (Meliaceae, sub-family Swietenioideae): Cedrela and Toona.
abstract: OBJECTIVE
  Floral development of Cedrela and Toona, the genera comprising the basal tribe Cedreleae of the sub-family Swietenioideae of Meliaceae, is described. The focus was on three endangered, ecologically and economically important species: Cedrela fissilis, Cedrela odorata and Toona ciliata. The aims of the study were to characterize the patterns of floral development in the tribe and to establish apomorphic and plesiomorphic floral characters in relation to other taxa within the family based on the current molecular phylogeny of Meliaceae.
  
  
  METHODS
  A detailed floral structural and developmental study was completed using both scanning electron microscopy and visualization of microtome sections with a light microscope.
  
  
  RESULTS
  Twelve floral developmental stages were identified. The initial development of the pentamerous flowers of both Toona and Cedrela is strikingly similar. The morphological differences observed between them are due to differential patterns of organ elongation and adnation/connation occurring late in development. Additionally, the formation of functionally male and female flowers was found to occur at specific positions within the inflorescence.
  
  
  CONCLUSIONS
  Due to the basal position of the tribe Cedreleae in the phylogeny of Meliaceae, functionally either male or female pentamerous flowers and the presence of (at least partially) free stamens may be considered plesiomorphic traits within the family. In contrast, sympetaly and the absence of nectaries in Cedrela species are synapomorphies.
authors.affiliation: Universidade de São Paulo, Centro de Energia Nuclear na Agricultura, Av. Centenário 303, CEP 13400-970, Piracicaba, SP, Brazil.
authors.forename: Cantídio Fernando
authors.initials: CF
authors.lastname: Gouvêa
authors.forename: Marcelo Carnier
authors.initials: MC
authors.lastname: Dornelas
authors.forename: Adriana Pinheiro Martinelli
authors.initials: AP
authors.lastname: Rodriguez
mesh_terms: D001947:Breeding; D031587:Cedrela / Q000033:anatomy & histology / Q000254:growth & development / Q000648:ultrastructure; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development* / Q000648:ultrastructure; D029582:Meliaceae / Q000033:anatomy & histology / Q000254:growth & development* / Q000648:ultrastructure; D018519:Meristem / Q000254:growth & development / Q000648:ultrastructure; D054817:Pollination / Q000502:physiology