<sod>  ''A cladogram showing the relationship between various plant groups using intersecting diagonal lines.''
 </div>
 
In a cladogram, all organisms lie at the endpoints, and each split is ideally binary (two-way).  The two taxa either side of a split are called ''sister taxa'' or ''sister groups''.  Each branch, whether it only contains one item or a hundred thousand, is called a ''clade''.  A correct cladogram should have all the organisms contained in any one clade share a unique ancestor for that clade, one which they do not share with any other organisms on the diagram.  Each clade should be set off by a series of characteristics that appear in its members but not in the other forms it diverged from.  These identifying characteristics of a clade are called ''synapomorphies'' (shared, derived characters).  For instance, hardened front [[wing]]s are a synapomorphy of [[beetle]]s, while [[Vernation|circinate vernation]], or the unrolling of new fronds, is a synapomorphy of [[fern]]s.
 
 ==Cladistic methods==
 
 
 ==Cladistic classification==
 
A recent trend in biology since the [[1960s]], called '''cladism''' or '''cladistic taxonomy''', is to require taxa (named groups in a [[taxonomy]]) to be clades.  In other words, cladists argue the classification system should be reformed to eliminate all non-clades (paraphyletic and polyphyletic groups).  In fact, some cladists have argued for entirely abandoning the [[Linnaean taxonomy|Linnaean]] system of ranked taxa in favor of clades.  A formal code of phylogenetic nomenclature, the [[PhyloCode]] [http://www.ohiou.edu/phylocode/], is currently under development for a cladistic taxonomy that abandons the Linnaean structure.
 
 A true clade is considered to be ''monophyletic'', or containing one (and only one) complete evolutionary grouping deriving from one common ancestor.  When a named group is found to contain more than one evolutionary line, it is termed ''polyphyletic''.  For example, the once-recognized group Pachydermata was found to be polyphyletic because an [[elephant]] and a [[rhinoceros]] were each found to be more closely related to non-pachyderms than either to each other.  Biologists consider groups that turn out to be polyphyletic to be errors in classification, often occurring because [[convergent evolution|convergence]] or other [[homoplasy]] was misinterpreted as [[homology (biology)|homology]].
 
 <eod> <sod> ''A cladogram showing the relationship between various plant groups using intersecting diagonal lines.''
 </div>
 
In a cladogram, all organisms lie at the endpoints, and each split is ideally binary (two-way). The two [[taxon|taxa]] either side of a split are called ''sister taxa'' or ''sister groups''. Each branch, whether it only contains one item or a hundred thousand, is called a ''clade''. A correct cladogram should have all the organisms contained in any one clade share a unique ancestor for that clade, one which they do not share with any other organisms on the diagram. Each clade should be set off by a series of characteristics that appear in its members but not in the other forms it diverged from. These identifying characteristics of a clade are called ''synapomorphies'' (shared, derived characters). For instance, hardened front [[wing]]s are a synapomorphy of [[beetle]]s, while [[Vernation|circinate vernation]], or the unrolling of new fronds, is a synapomorphy of [[fern]]s.
 
 ==Cladistic methods==
 
 
 ==Cladistic classification==
 
A recent trend in biology since the [[1960s]], called '''cladism''' or '''cladistic taxonomy''', is to require taxa to be clades. In other words, cladists argue the classification system should be reformed to eliminate all non-clades (paraphyletic and polyphyletic groups). In fact, some cladists have argued for entirely abandoning the [[Linnaean taxonomy|Linnaean]] system of ranked taxa in favor of clades. A formal code of phylogenetic nomenclature, the [[PhyloCode]] [http://www.ohiou.edu/phylocode/], is currently under development for a cladistic taxonomy that abandons the Linnaean structure.
 
 A true clade is considered to be ''monophyletic'', or containing one (and only one) complete evolutionary grouping deriving from one common ancestor.  When a named group is found to contain more than one evolutionary line, it is termed ''polyphyletic''.  For example, the once-recognized group Pachydermata was found to be polyphyletic because an [[elephant]] and a [[rhinoceros]] were each found to be more closely related to non-pachyderms than either to each other.  Biologists consider groups that turn out to be polyphyletic to be errors in classification, often occurring because [[convergent evolution|convergence]] or other [[homoplasy]] was misinterpreted as [[homology (biology)|homology]].
 
 <eod>