Floral development of Dieffenbachia and the occurrence of atypical flowers in Araceae.

Denis Barabé,Christian Lacroix

doi:10.1186/1999-3110-55-30

Denis Barabé, Christian Lacroix

Open Access

https://doi.org/10.1186/1999-3110-55-30

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Abstract

BackgroundThe floral development of Dieffenbachia seguine (N. J. Jacquin) Schott is analysed in relation to the molecular phylogeny of the Spathicarpae by Cusimano et al. (Am J Bot 98:654–668, 2011).ResultsThe initiation of discoid floral primordia occurs acropetally on the surface of the spadix. Female flowers, atypical bisexual flowers, sterile male flowers, and male flowers share the same phyllotactic spirals on the spadix. Four or five stamen primordia are initiated simultaneously on the periphery of the male floral meristem. During early stages of stamen initiation, individual stamen primordia are connate at their base. In a synandrium, stamen fusion occurs very early during their developmental cycle with the stamens being already united laterally when longitudinal elongation occurs. The staminodes are also initiated on the periphery of the discoid floral primordium, and their number varies from four to six. The development of the fused staminodes will eventually form a longitudinal cavity in the center of the mature synandrode. The atypical flowers located in the intermediate zone range in morphology from aborted female flowers to rudimentary sterile male flowers with incomplete staminodes.ConclusionsThe development of the female flower of Dieffenbachia Schott presents some similarities with atypical bisexual flowers of Cercestis Schott representing one of three types of aberrant flower forms in the family. From a developmental point of view and in the context of a phylogeny of the group, we believe that the presence of staminodes in the female zone constitutes a plesiomorphy in the tribe Spathicarpeae.Electronic supplementary materialThe online version of this article (doi:10.1186/1999-3110-55-30) contains supplementary material, which is available to authorized users.

Highlights

IntroductionThe flowers of the Araceae represent a good model for conducting comparative developmental studies at different hierarchical levels
Morphology of mature flowers and inflorescences Dieffenbachia seguine is a more or less rhizomatous plant that usually grows in open undergrowth
The female zone is completely adnate to the spathe on one side

Summary

Introduction

The flowers of the Araceae represent a good model for conducting comparative developmental studies at different hierarchical levels. The elongate spadix consisting of unisexual flowers in many genera offers the possibility to study the transition from female to male flowers from a developmental point of view. Recent well resolved molecular phylogenies (Cabrera et al, 2008; Cusimano et al, 2011), allow us to integrate floral developmental morphology in the context of a rigorous systematic framework. As the largest subfamily of the Araceae, Aroideae consists of 81 genera (Boyce and Croat, 2011). This group is generally characterised by unisexual flowers arranged in well-delineated zones on the spadix. The female flowers are located in the lower portion of the spadix and the male flowers (sterile and fertile) are found directly above

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