Analysis of rhizome morphology of the Zingiberales in Payamino (Ecuador) reveals convergent evolution of two distinct architectural strategies

Abstract

Rhizome morphology of 18 Zingiberales species growing in situ in lowland Ecuadorian rainforest (Payamino) covering six of the eight families of the order is presented. Phenetic and morphological analyses reveal two strategies that vary starkly in their mode of construction and geometry. Furthermore, parsimony-based character evolution in a resolved phylogenetic framework identifies convergent evolution of these strategies. The two strategies uncovered by the phenetic and morphological analyses are correlated with branching localization and timing: species showing delayed, non-positional- preferential branching exhibit poorly predictable, non-geometric rhizomes whereas species exhibiting immediate branching occurring at specific internodes display predictable, highly geometric rhizome morphologies. Hence, the control of two simple developmental parameters defines two distinct modes of construction in basitonically branched, rhizomatous plants. Multiple switches in the state of these characters during the evolution of Zingiberales resulted in diversification and convergence of rhizome morphologies in the order. © 2013 Société botanique de France.