title: Palynological variation in balsaminoid ericales. I. Marcgraviaceae.
abstract: OBJECTIVE
  Marcgraviaceae are a rather small family of seven genera and approx. 130 neotropical species. This study aims to present a detailed palynological survey of the family in order to comment on the intrafamily relationships and possible correlations with pollinators.
  
  
  METHODS
  In total, 119 specimens representing 67 species and all genera are observed using light microscopy and scanning electron microscopy. Furthermore, eight species from five genera are studied with transmission electron microscopy.
  
  
  RESULTS
  Our results show that pollen grains of Marcgraviaceae are small (20-35 microm), have three equatorial apertures, granules on the colpus membrane, oblate spheroidal to prolate spheroidal shapes, mainly psilate to perforate ornamentations, and lalongate colpus-shaped thinnings at the inner layer of the exine, and show the presence of orbicules. Based on our fragmentary knowledge of the pollination biology of the family, there are no clear correlations between pollinators and pollen features.
  
  
  CONCLUSIONS
  The genus Marcgravia has a high percentage of reticulate sexine patterns and a relatively thin nexine. Sarcopera can be defined by the presence of an oblate spheroidal to even suboblate shape, while Ruyschia and Souroubea typically show prolate spheroidal to subprolate pollen grains. The presence of a thick foot layer in the pollen wall is characteristic of the genera Norantea, Sarcopera and Schwartzia. Pollen features that are taxonomically useful within the family are the shape, sexine sculpturing, and ultrastructure of the pollen wall.
authors.affiliation: Laboratory of Plant Systematics, Institute of Botany and Microbiology, K.U.Leuven, Kasteelpark Arenberg 31, B-3001 Leuven, Belgium. frederic.lens@bio.kuleuven.ac.be
authors.forename: Frederic
authors.initials: F
authors.lastname: Lens
authors.forename: Stefan
authors.initials: S
authors.lastname: Dressler
authors.forename: Stefan
authors.initials: S
authors.lastname: Vinckier
authors.forename: Steven
authors.initials: S
authors.lastname: Janssens
authors.forename: Steven
authors.initials: S
authors.lastname: Dessein
authors.forename: Liesbeth
authors.initials: L
authors.lastname: van Evelghem
authors.forename: Erik
authors.initials: E
authors.lastname: Smets
mesh_terms: D014644:Genetic Variation; D010944:Plants / Q000145:classification / Q000235:genetics / Q000648:ultrastructure*; D011058:Pollen / Q000145:classification / Q000235:genetics / Q000648:ultrastructure*; D013045:Species Specificity