Chemotaxonomic significance of hydroxylated pipecolic acids in Central American Inga (Fabaceae: Mimosoideae: Ingeae)

Hydroxylated pipecolic acid derivatives of 47 species of Inga were analyzed primarily from herbarium leaf samples supplemented by field collections. Inga species are noted for their morphological variability, which has resulted in considerable taxonomic confusion. Pipecolic acid chemistry appears to be a relatively stable character within species, and the large number of pipecolic acid derivatives translates to greater intraspecific diversity in chemical patterns (18 distinct hydroxypipecolic acid patterns) than previously found in related genera. This chemical diversity makes pipecolic acids particularly useful in solving taxonomic problems in this genus; problems such as identification of distinct species with convergent morphology and identification of mislabeled herbarium specimens. Chemistry provides data independent of morphology with which to assess recent changes in nomenclature (some of which are supported, others not) and may also be useful in the assessment of hybridization and in delimitation of proper species boundaries. Al present our chemical knowledge is too fragmentary to allow strong statements regarding relationships above the species level, but there is a trend for taxa traditionally grouped on morphological criteria to share similar chemistries. (C) 1998 Elsevier Science Ltd. All rights reserved.