title: The structure of colleters in several species of Simira (Rubiaceae).
abstract: OBJECTIVE
  Colleters are secretory structures consisting of a parenchymatic middle axis surrounded by a layer of palisade-like epidermal cells. Colleters occur in a large number of rubiaceous species. Their function is to protect the developing shoot apex. They are also taxonomically useful in the Rubiaceae. This study characterized the structure of the colleters of Simira glaziovii, S. pikia and S. rubra and the biochemistry of secretions in S. glaziovii.
  
  
  METHODS
  Stipules of the shoot apices of the three species studied were collected at Barragem de Saracuruna, in Rio de Janeiro state, Brazil. The samples were fixed according to the usual methods for light and electron microscopy. Secretion stipules of S. glaziovii were washed with 0.1 m Tris-HCl plus 0.1 %Triton X-100 to extract proteins and carbohydrates.
  
  
  RESULTS
  Colleters in these species are located at the base of the stipule. Each species shows a different pattern of distribution. They form as emergentia from the stipules. Simira glaziovii was different from the other two species because it exhibited vascular traces. The epidermal cells of colleters have dense cytoplasm, nuclei, small vacuoles, endoplasmic reticulum, Golgi apparatus, mitochondria and extraplasmic spaces if they are secretory. The outer cell wall of the mature colleters differs from the outer cell wall of stipule cells and immature colleters. Both carbohydrates and proteins were found in secretions from the stipules of S. glaziovii.
  
  
  CONCLUSIONS
  Few ultrastructural differences were noted among the three species. These secretory structures not only protect the shoot apex, but also have taxonomic importance below the genus level.
authors.affiliation: Laboratório de Biologia Celular e Tecidual, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense.
authors.forename: Denise Espellet
authors.initials: DE
authors.lastname: Klein
authors.forename: Valdirene
authors.initials: V
authors.lastname: Moreira Gomes
authors.forename: Sebastião José
authors.initials: SJ
authors.lastname: DA Silva-Neto
authors.forename: Maura
authors.initials: M
authors.lastname: DA Cunha
mesh_terms: D004847:Epithelial Cells / Q000502:physiology / Q000648:ultrastructure; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D019666:Rubiaceae / Q000033:anatomy & histology* / Q000502:physiology / Q000648:ultrastructure; D013045:Species Specificity