There will be traces: exploring the atypical floral vasculature of Swartzia panacoco and Swartzia polyphylla (Leguminosae-Papilionoideae)
2025
Zalko, Julie | Génétique Quantitative et Evolution - Le Moulon (Génétique Végétale) (GQE-Le Moulon) ; AgroParisTech-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | DIM-MAP (Domaine de recherche et d'Innovation Majeurs-Materiaux Anciens et Patrimoniaux) Ile de France
International audience
Afficher plus [+] Moins [-]anglais. The genus Swartzia (Papilionoideae) exhibits a unique combination of floral characteristics within the subfamily, including the reduction of perianth parts, numerous stamens initiated as a ring meristem, heteromorphic androecium and free filaments. This study presents a detailed analysis of the floral vasculature in Swartzia examined comparatively to the vasculature of typical papilionate flowers. Preanthetic floral buds of Swartzia panacoco and S. polyphylla were selected from herbarium specimens, cut in serial transverse sections and studied with light microscope. Both species are characterized by a singular configuration of vascular characteristics 1) a trihiate vascular organization with three separate whorls of traces, with each whorl diverging from the stele in centripetal order, 2) a large stele that supplies the numerous small stamens and 3) the connection of the large stamen traces with the solitary petal. The trihiate organization in S. panacoco and S. polyphylla, the only reported cases in the subfamily, might be the consequence of the differences in the position and timing of stamen development compared to other floral parts. Given that the ring meristem seems responsible for this condition in Swartzia, it may also be involved in the enlargement and modification of the stele in both species. The connection between the petal traces and the large stamen traces as they leave the stele is likely due to a reduction in the number of floral parts, causing these structures to come closer together. This study illustrates the inherent link between floral development and vascular anatomy in Papilionoideae.
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