Comparative floral development reveals novel aspects of structure and diversity of flowers in Cannabaceae

Author(s)
Flávia M Leme, Jürg Schönenberger, Yannick M Staedler, Simone P Teixeira
Abstract

Species of Cannabaceae are wind pollinated, have inconspicuous and reduced flowers that are pistillate, staminate and apparently perfect on the same individual or on different individuals, with a single-whorled perianth and a pseudomonomerous gynoecium. Our objective is to understand the developmental processes that lead to such a reduced flower morphology and polygamy in Cannabis sativa, Celtis iguanaea and Trema micrantha. Floral buds and flowers were processed for surface, histological examinations and 3D reconstructions of vasculature. The single-whorled perianth is interpreted as a calyx because the organs are robust, have a broad base, an acute apex and quincuncial aestivation and are opposite the stamens. Petals are absent from inception. The dicliny is established at different development stages: stamens or carpels are absent from inception (Cannabis sativa), initiated and aborted during early (Trema micrantha, before sporo/gametogenesis) or late (Celtis iguanaea, after sporo/gametogenesis) development. Furthermore, in all species studied the carpels are congenitally united and the pseudomonomerous nature of the gynoecium is confirmed. Glandular trichomes are distributed on the bracts, sepals, anther connective and receptacle. Special floral features shared by species of Cannabaceae include precocious ovule development and sepals that are each vascularized by one bundle. The reduced flowers of Cannabaceae are the result of the absence from inception and/or abortion of organs and even of a whole whorl at different developmental stages, which were probably selected in response to pressures exerted by the similar pollination mechanism.

Organisation(s)
Department of Botany and Biodiversity Research
External organisation(s)
Universidade Federal de Mato Grosso do Sul, University of Sao Paulo
Journal
Botanical Journal of the Linnean Society
Volume
193
Pages
64-83
ISSN
0024-4074
DOI
https://doi.org/10.1093/botlinnean/boaa004
Publication date
02-2020
Peer reviewed
Yes
Austrian Fields of Science 2012
106042 Systematic botany, 106008 Botany, 106012 Evolutionary research
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/comparative-floral-development-reveals-novel-aspects-of-structure-and-diversity-of-flowers-in-cannabaceae(885cdfbd-02dc-4ab0-b99e-e9b8ee8b3d11).html