title: Equisetum species show uniform epicuticular wax structures but diverse composition patterns.
abstract: OBJECTIVE
  Only few data on the epicuticular waxes (EWs) of horsetails are available. This contribution therefore focuses on the wax micromorphology and chemical composition of Equisetum species of the subgenera Equisetum and Hippochaete.
  
  
  METHODS
  Distribution patterns and structural details of EW on the shoots were studied by scanning electron microscopy. After extraction with chloroform, the chemical composition of wax isolates was analysed by gas chromatography.
  
  
  RESULTS
  Epicuticular wax crystals were non-oriented platelets or membraneous platelets. They were usually located on subsidiary cells of stomata and adjacent cells. Other parts of the shoots were covered mainly with a smooth wax film or small granules only. The chemical constituents found were alkanes, esters, aldehydes, primary alcohols and free fatty acids in a range of C(20)-C(36) (in esters C(36)-C(56)). All species of the subgenus Hippochaete showed a similar pattern of fractions with high percentages of alkanes and aldehydes, whereas the subgenus Equisetum species had distinctly different wax compositions. Extracts from the internodes-surfaces without well-developed EW crystals and only few stomata-showed the lowest contents of aldehydes.
  
  
  CONCLUSIONS
  The covering with EW crystals will provide unhindered gas exchange and, combined with intracuticular wax, may prevent excess water loss during winter in the evergreen shoots of the subgenus Hippochaete. The results indicate that the Equisetum wax micromorphology and biosynthesis are comparable to EW of other pteridophyte classes and mosses.
authors.affiliation: Institute of Botany ,  University of Hohenheim ,  Garbenstrasse 30, D-70593 Stuttgart ,  Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brune
authors.forename: Klaus
authors.initials: K
authors.lastname: Haas