Variation in Indumentum Morphology in the Melaleuca leucadendra Complex (Myrtaceae)

Abstract

A light and scanning electron microscope study of variation in leaf hairs in the Melaleuca leucadendra complex is described as a precursor to a taxonomic revision. The indumentum is homogeneous with respect to cellular structure, the hairs being simple, unicellular and unbranched. Hairs of different lengths are produced, with shorter hairs possibly produced later than the longer ones. The shorter hairs tend to be bent or crisped. There is diversity in the degree of crisping of short hairs which appears to be genetically based and this attribute is of some value as a diagnostic character. Two apparent geographical subspecies of M. nervosa are distinguished by differences in crisping of the shorter hairs. However similarities with hair patterns in other species suggest polyphylesis, and raise questions of natural relationships between entities within the M. leucadendra complex.