Complex interspecific interactions in Eucalyptus: evidence from the chloroplast

[First paragraphs] Eucalyptus L'Herit. is one of Australia's largest genera, with over 700 species (Brooker & Kleinig 1994). Despite its importance in the Australian flora and in the Australian economy, numerous questions of systematic relationships within the genus remain to be addressed. The series Viminales (subgenus Symphyomyrtus) contains about 40 species, is characterised by markedly different adult and juvenile foliage, and includes Australia's most important temperate hardwood plantation species (E. nitens, E. globulus). Despite numerous morphological studies and some chemical studies, the delimitation and subdivision of species within the series Viminales remain problematic (Chappill & Ladiges 1996). In cases where morphology has not effectively resolved phylogenetic relationships among taxa, chloroplast DNA has frequently proved to be highly informative at the species level and above. By cutting the DNA with specific enzymes, a 'fingerprint' of the cpDNA can be constructed. A particular chloroplast DNA 'fingerprint' is often referred to as a 'haplotype' (a haploid genotype).