Comparative morphology and anatomy of cypselae in Piptolepis (Vernonieae, Asteraceae) with emphasis on the pappus systematic significance

• Published in: Flora. Morphologie, Geobotanik, Oekophysiologie Geobotanik, Oekophysiologie, 2022-02, Vol.287, p.151988, Article 151988
• Main Authors: Marques, Danilo, Cândido, Jacqueline Bonfim e, Loeuille, Benoît, Marzinek, Juliana
• Format: Article
• Language: English
• Subjects: Achene; Compositae; Fruit; Lychnophorinae; Pericarp
• ISSN: 0367-2530; 1618-0585
• DOI: 10.1016/j.flora.2021.151988

•Pappus serie is important to evolutionary history of Piptolepis.•Vestigial pappus brings new evolutionary perspectives of the pappus in lychnophorinae.•Cypsela morphology was relevant to delimitation of species of Piptolepis. Comparative studies of cypselae from Asteraceae have revealed traits of high taxonomic value. The pappus structure, cypsela shape, indument, pericarp structure and its variations between groups are robust features that help assessing the family's evolutionary history. Systematic knowledge has advanced in the subtribe Lychnophorinae (tribe Vernonieae), and the evolution of specific structures has been debated. Thus, we carried out the first morphoanatomical study of the cypselae in Piptolepis (Lychnophorinae), searching for morphological variations to help classify the group and understand its evolutionary history. Cypselae were studied using scanning electron microscopy and historesin inclusion techniques. Our results showed that collenchymatic tissue in the outer mesocarp in Piptolepis distinguishes it from other Vernonieae studied so far. Furthermore, some pappus characteristics such as type, number of series, duration, and lateral projections, and cypsela features such as shape, presence of crystals in the outer mesocarp and occurrence of carpellary bundles may help identify some closely related species. A vestigial pappus series in Piptolepis shed light on the evolutionary history of genus and Lychnophorinae as a whole.