Morphology of inflorescences in Verbenaceae-Verbenoideae II: Tribe Petreeae

Abstract

This paper deals with the interpretation, description and typological characterization of the inflorescences of the following genera of the tribe Petreeae Briq.: Petrea L., Xolocotzia Miranda and Recordia Moldenke. All of them have a polytelic type of synflorescence. Florescences of all genera are racemes with decussate bracts. The heterothetic diplobotryum is present in Recordia and also in several
species of Petrea. Truncation of the main florescence has been found in P. maynensis J. Huber, P. volubilis L. and P. pubescens Turcz. giving rise to an homothetic diplobotryum. Suppression of the enriching zone occurs in Xolocotzia, Recordia and some species of Petrea. Xolocotzia has monobotrya and reduction of flower number within the florescences. In the monobotrya the pair of leaves preceding the basal internode is bracteose and bears axillary resting buds. In the heterothetic diplobotryum this node represents an intercalar inhibition zone. Some Petrea species show aborted accesory paraclades. These arise from the accesory axillary buds of the enrichment zone. According to this study, the heterothetic pleiobotryum has been considered as a primitive or central form, from which monobotrya derived through processes of suppression of the enrichment zone, and homothetic pleiobotrya, by suppression of the main florescence (truncation). The use of inflorescence characters for a cladistic analysis accomplished by Rueda (1994) for the genus Petrea, are discussed.