This function writes trees in a file with the NEXUS format.
write.nexus(..., file = "", translate = TRUE)None (invisible `NULL').
either (i) a single object of class "phylo", (ii) a
    series of such objects separated by commas, or (iii) a list
    containing such objects.
a file name specified by either a variable of mode character,
    or a double-quoted string; if file = "" (the default) then the
    tree is written on the standard output connection.
a logical, if TRUE (the default) a translation
    of the tip labels is done which are replaced in the parenthetic
    representation with tokens.
Emmanuel Paradis
If several trees are given, they must all have the same tip labels.
If among the objects given some are not trees of class "phylo",
  they are simply skipped and not written in the file.
See write.tree for details on how tip (and node) labels
  are checked before being printed.
Maddison, D. R., Swofford, D. L. and Maddison, W. P. (1997) NEXUS: an extensible file format for systematic information. Systematic Biology, 46, 590--621.
read.nexus, read.tree,
  write.tree, read.nexus.data,
  write.nexus.data