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<p>Native to the American continent, the genus <i>Hippeastrum</i> Herb. is distributed from Mexico to Argentina. In Brazil, it is represented by approximately 30 species. This study examined the pollen grains of 20 taxa within the genus to determine whether differences in pollen morphology could support a clearer delimitation and characterization of subgenera and subordinate species. Pollen grains were treated with 40% lactic acid, measured, described, and photomicrographed. Non-acetolyzed pollen grains were examined using scanning electron microscopy. The pollen grains are large to very large, monads, monosulcate, elliptical in polar view, with reticulate or retipilate sexine. Species with retipilate exine were differentiated based on pilum arrangement and density, while those with reticulate exine were distinguished by muri width, lumen diameter, and columellae. Qualitative and quantitative data allowed the development of a diagnostic key and multivariate analyses (PCA and cluster analysis) revealed morphological groupings that, while informative at the species level, did not consistently support subgeneric classifications. The results reinforce the value of pollen characters for species circumscription but suggest limited utility in resolving infrageneric relationships within <i>Hippeastrum.</i></p>

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Pollen morphology of Hippeastrum (Amaryllidaceae): implications for taxonomic delimitation and systematics

  • 期刊论文

  • 发表日期：

    2025年8月6日

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  • Renata Suzano Cândido,
  • Rosana Conrado Lopes,
  • Cláudia Barbieri Ferreira Mendonça,
  • Vania Gonçalves-Esteves

摘要

Native to the American continent, the genus Hippeastrum Herb. is distributed from Mexico to Argentina. In Brazil, it is represented by approximately 30 species. This study examined the pollen grains of 20 taxa within the genus to determine whether differences in pollen morphology could support a clearer delimitation and characterization of subgenera and subordinate species. Pollen grains were treated with 40% lactic acid, measured, described, and photomicrographed. Non-acetolyzed pollen grains were examined using scanning electron microscopy. The pollen grains are large to very large, monads, monosulcate, elliptical in polar view, with reticulate or retipilate sexine. Species with retipilate exine were differentiated based on pilum arrangement and density, while those with reticulate exine were distinguished by muri width, lumen diameter, and columellae. Qualitative and quantitative data allowed the development of a diagnostic key and multivariate analyses (PCA and cluster analysis) revealed morphological groupings that, while informative at the species level, did not consistently support subgeneric classifications. The results reinforce the value of pollen characters for species circumscription but suggest limited utility in resolving infrageneric relationships within Hippeastrum.