Essential Oils as Taxonomic Criteria in Bothriochloa

Abstract

Essential oils extracted from the inflorescences of 17 species of Bothriochloa O. Kuntze (Gramineae) were analyzed by means of a gas-liquid chromatograph. The presence or absence of peaks on the chromatograms, as well as the relative amounts of these chemical components, can be used as taxonomic criteria. Species were found to be chemically unique, except for those that form interspecific agamic complexes. In these agamospecies, as well as in sexually reproducing species, chemical, morphological, and genetic data are closely correlated. The chromatograms could be reproduced exactly from samples of the same collection obtained at different times of the growing season, as well as from the same collection grown in the greenhouse or in the field. As inflorescence structure is strongly influenced by growing conditions, chemical data often were found to be more reliable than gross morphological characters in determining species affinities.