Souza Lukas Gabriel Macedo Pessanha de, Falcão Marcus José de Azevedo, Basso-Alves João Paulo, Mansano Vidal de Freitas
Instituto de Pesquisas Jardim Botânico Do Rio de Janeiro (JBRJ), Diretoria de Pesquisa Científica, Rio de Janeiro, RJ, 22460-030, Brazil.
Programa de Pós-Graduação em Botânica da Escola Nacional de Botânica Tropical, JBRJ, Rua Pacheco Leão, 2040, Solar da Imperatriz, Horto, Rio de Janeiro, 22460‑030, Brazil.
J Plant Res. 2025 Mar;138(2):253-272. doi: 10.1007/s10265-024-01610-8. Epub 2024 Dec 27.
Erythrina is a Pantropical bird-pollinated genus of Fabaceae. Thus, its flowers are usually large, showy, red or yellowish, offering nectar as the principal resource. There are two main interaction systems with birds in Erythrina: in one, the inflorescences are erect and the flowers are horizontal, offering no landing platform; in the other, the inflorescences are horizontal and the flower parts are more exposed. Erythrina speciosa is pollinated by hummingbirds and E. poeppigiana is pollinated by passerines. Despite their structural variation, little is known about how species of the same genus diverge ontogenetically to form flowers adapted to pollinators with different beak morphology and feeding behaviors. Therefore, this study aimed to investigate floral development in two species according to their pollination system. Flowers and buds were collected and fixed for analysis using scanning electron microscopy and light microscopy. Some characteristics are common to both species: the formation of a pseudoracemose inflorescence, the unidirectional emergence of floral organs, and the formation of a short staminal sheath involving nine of the ten stamens (diadelphous androecium). Other characteristics, notably those related to the late stages of floral development, gradually diverged. Among them are inflorescence formation pattern; the formation of reduced and free keel petals in E. speciosa, while in E. poeppigiana they are longer and postgenitally united by their lower margins; and the participation of the standard in the floral display. The studied species share several traits common to other Papilionoideae, but some similarities between the species studied may not be phylogenetically related and reveal the potential ontogenetic pathways of functional convergence that flowers have experienced throughout evolution in the genus.
刺桐属是豆科中一个由鸟类传粉的泛热带属。因此，其花朵通常较大、艳丽，呈红色或淡黄色，花蜜是主要的资源。刺桐属与鸟类有两种主要的相互作用系统：一种是花序直立，花朵水平，不提供着陆平台；另一种是花序水平，花部更外露。美丽刺桐由蜂鸟传粉，而佩氏刺桐由雀形目鸟类传粉。尽管它们在结构上存在差异，但对于同一属的物种如何在个体发育上发生分化以形成适应具有不同喙形态和取食行为传粉者的花朵，人们了解甚少。因此，本研究旨在根据两种刺桐的授粉系统来研究其花的发育。采集花朵和花蕾并固定，以便使用扫描电子显微镜和光学显微镜进行分析。两种物种有一些共同特征：形成假总状花序、花器官单向出现，以及形成一个短的雄蕊鞘，包含十枚雄蕊中的九枚（二体雄蕊）。其他特征，特别是与花发育后期相关的特征，逐渐出现分化。其中包括花序形成模式；美丽刺桐中龙骨瓣缩小且分离，而在佩氏刺桐中它们更长，且在基部边缘合生；以及旗瓣在花展示中的参与情况。所研究的物种具有其他蝶形花亚科共有的几个特征，但所研究物种之间的一些相似性可能并非系统发育相关，而是揭示了该属花朵在整个进化过程中经历的功能趋同的潜在个体发育途径。
