Taxonomic significance of Cyspsela in Vernonia anthelmintica Willd. and V. cinerea Less. (Asteraceae; tribe – Vernonieae): Structural manifestations

Abstract

An investigation was carried out to reveal the taxonomic importance of cypselar features of Vernonia anthelmintica Willd. and Vernonia cinerea Less. through morpho-anatomical manifestations in the plesiomorphic tribe Vernonieae of the dicot family Asteraceae. A light microscopic (LM) and Scanning Electron Microscopic (SEM) study unraveled various morphological features of the cypsela. Among them, apical part, wall surface, surface hairs, nature, structure and arrangement of carpopodium, and stylopodium are taxonomically important traits. Furthermore, presence or absence of glands in wall surface, pappus bristles, testal nature, distribution of crystal and in pericarp and/or testa and endosperms of cypselas can also be considered as taxonomically significant. Distinct differences were observed between two taxa for many characteristics. Notable among these were occurrence of stylopodium, size of cypsela (without pappus), nature of pappus, thickness of pericarp, presence or absence of ribs, layer of radially elongated cells in mesocarpic sclerenchyma ans parenchyma, presence of additional uniseriate palisade like sclerenchymatous layer in V. anthelmintica, but not in V. cinerea, testal epidermal layer, nature of endosperm layer, and crystal formation. Similarities between two taxa were also noted. Based on structural manifestations of cypsela at morphoanatomical levels, an indented dichotomous key is provided for identification of studied taxa.

Fruit of Lepidaploa (Cass.) Cass. (Vernonieae, Asteraceae): anatomy and taxonomic implications

“…The exotesta of the seeds of L. psylostachya and L. tarijensis possess a secondary wall in the anticlinal and periclinal walls, and only in the anticlinal wall, respectively. The presence of a secondary wall of the exotesta was also reported in Vernonia anthelmintica, which exhibited U-shaped lignification (Talukdar 2015).…”

“…Meanwhile, Lessingianthus brevifolius (Martins & Oliveira 2007), a species of the sister genus of Chrysolaena and Lepidaploa, exhibited only one layer of cells in the outer mesocarp, and so may represent a taxonomic difference between Chrysolaena + Lepidaploa and Lessingianthus, if this same pattern is confirmed in the other species of Lessingianthus. Although this character is sufficient to differentiate Lessingianthus brevifolius from the other two genera, the number of cell layers must be used with care in the taxonomy of the group, since there are records in the literature of variation in the number of layers in different regions of the same fruit, as reported for Cyanthillium cinereum (Tiagi & Taimni 1960;Pandey & Singh 1980), V. fasciculata, V. missurica (Pandey & Singh 1980), and V. anthelmintica (Misra 1972;Pandey & Singh 1980;Talukdar 2015).…”

“…Although Vernonieae exhibits a high degree of morphological variability, the tribe is generally known for its alternate leaves, discoid heads with violet flowers, acute style branches and biseriate pappus (Keeley & Robinson 2009). The cypselae of Vernonieae are generally cylindrical or turbinate, sometimes prismatic, and brown (Semir et al 2011;Marques & Dematteis 2014;Angulo et al 2015;Talukdar 2015;Redonda-Martínez et al 2017;Pico et al 2016). The pappus can be biseriate with an outer short paleaceous series and an inner long bristle series (Marques & Dematteis 2014;Angulo et al 2015;Redonda-Martínez et al 2017;Pico et al 2016), biseriate with two paleaceous series (one short and one long) (Semir et al 2011), or it can be absent (Redonda-Martínez et al 2017).…”

“…Due to the taxonomic importance of cypselae for the delimitation of subtribes, genera and species of Vernonieae, numerous anatomical studies have been performed with taxa of this tribe (Misra 1972;Pandey & Singh 1980;Mukherjee & Sarkar 2001;Martins & Oliveira 2007;Galastri & Oliveira 2010;Jana & Mukherjee 2013;Freitas et al 2015;Talukdar 2015;Redonda-Martínez et al 2017). Most of the African and Asian species of Vernonieae that have been studied anatomically have revealed that the anatomy of the cypselae is very important to the taxonomy valuable of the tribe (Mukherjee & Sarkar 2001;Jana & Mukherjee 2013;Talukdar 2015). Some American species have also been studied, and their anatomical characters have also proven to be important to the taxonomy of the group (Martins & Oliveira 2007;Galastri & Oliveira 2010;Freitas et al 2015;Redonda-Martínez et al 2017).…”

Structure of the seed coat of the Asteraceae species. I. Tribes Arctotideae, Cardueae, Mutisieae, Vernonieae

“…Многие авторы, исследующие строение семянок Vernonieae (Isawumi, 1999;Jana, Mukherjee, 2012Talukdar, 2015), отмечают, что теста плотно прижата к перикарпию и её признаки имеют важное значение в таксономии трибы. Согласно данным N. Galastri и D. Oliveira (2010), исследовавшим развитие плодов Vernonia platensis (Spreng.)…”