Plant structure ontology : How should we label plant structures with doubtful or mixed identities ? *

.......................................................................................................................................................................... 103 Introduction ..................................................................................................................................................................... 104 Morphological nomenclature: The Plant Structure Ontology ......................................................................................... 104 Case studies ..................................................................................................................................................................... 105 “Leaves” ................................................................................................................................................................... 105 “Roots” ..................................................................................................................................................................... 108 “Flowers” .................................................................................................................................................................. 110 Morphological nomenclature: five complementary approaches ..................................................................................... 112 Approach 1 = Standardized vocabularies ................................................................................................................. 112 Approach 2 = Developmental genetics .................................................................................................................... 112 Approach 3 = Continuum Model and Fuzzy Morphology ....................................................................................... 113 Approach 4 = Process morphology, i.e. dynamic morphology ................................................................................ 114 Approach 5 = Character cladograms ........................................................................................................................ 117 Conclusions and outlook ................................................................................................................................................. 119 Acknowledgments ........................................................................................................................................................... 120 References ....................................................................................................................................................................... 120