Inflorescence Structure in Laurales-Stable and Flexible Patterns

Premise of research. This is the first comparative study of inflorescence morphology through all seven families of the order Laurales (Atherospermataceae, Calycanthaceae, Gomortegaceae, Hernandiaceae, Lauraceae, Monimiaceae, and Siparunaceae) and the larger subclades of these families. Methodology. We studied 89 species of 39 genera from herbarium specimens and partly from liquid-fixed material, focusing on the branching patterns in the reproductive region. In addition, we used the information from the literature. Pivotal results. There are recurrent branching patterns. Botryoids, thyrsoids, and compound botryoids and thyrsoids are the most common forms. Panicles, racemes, and thyrses are rare. Panicles and racemes occur in some highly nested Lauraceae and thyrses in Hernandiaceae. Thus, the presence of thyrso-paniculate inflorescences is not characteristic for Laurales, in contrast to the statement by Weberling. Conclusions. An evolutionary interpretation is still difficult because the existing molecular phylogenetic analyses are not fine grained enough and also because the previous phylogenetic results are not robust enough to make firm conclusions within the order. However, the present structural results show that there are trends of occurrence of certain patterns in families or subclades within families, and these may be useful in a morphological matrix of magnoliids (see work by Doyle and Endress for basal angiosperms).