Anatomy of vegetative organs with an emphasis on the secretory structures of two species of Aldama (Asteraceae–Heliantheae)

Abstract

Aldama arenaria (Baker) E.E.Schill. & Panero and Aldama robusta (Gardner) E.E.Schill. & Panero are aromatic plants, morphologically very similar and usually confused on the analysis of exsiccates. The present study aimed to identify the secretory structures present in vegetative organs and to survey for anatomical features with diagnostic value between A. arenaria and A. robusta based on an examination of these organs. Aldama arenaria and A. robusta exhibit hydathodes in the dentate ornamentations of the leaf margins and apices in addition to glandular trichomes, secretory cavities and ducts, all of which vary with respect to type and location in each species. Xylopodia and adventitious roots constitute the underground system. The xylopodium is covered by epidermis or by suberised cells resulting from periclinal divisions of parenchyma cells. The tuberisation process of adventitious roots results mainly from hypertrophy and hyperplasia of medullary cells, especially in A. arenaria. Through anatomical analysis, useful features for distinction between A. arenaria and A. robusta in exsiccates and fresh materials were identified, and these features were related mainly to the position and frequency of secretory structures.

Can climate and soil conditions change the morpho-anatomy among individuals from different localities? A case study in Aldama grandiflora (Asteraceae)

“…Although literature shows that aluminum and iron toxicity at low pH can directly influence plant development (Lopes and Cox, 1977;Haridasan, 2008), leading to the development of scleromorphic characters in cerrado plants (Goodland, 1971), the levels of iron and aluminum in the soil did not harm the development of Aldama grandiflora plants. Furthermore, A. grandiflora showed an anatomical stem development very similar to other species of the group already described (Bombo et al, 2012(Bombo et al, , 2014Oliveira et al, 2013;Silva et al, 2014;Bombo et al, 2016), indicating a consistency within the genus and that this species is well adapted to these soil conditions. In this study, A. grandiflora showed considerably consistency in leaf and stem anatomical characteristics since only slight morphometric differences were found among the populations analyzed.…”

“…Leaves characters such as the type and position of secretory structures have been useful for species differentiation (Castro et al, 1997;Fahn, 2000;Oliveira et al, 2013), including in Asteraceae (Solereder, 1908;Metcalfe and Chalk, 1950;Wagenitz, 1976;Castro et al, 1997;Adedeji and Jewoola, 2008;Fritz and Saukel, 2011). However, some studies (Kakrani et al, 1991;Sheue et al, 2003;Filartiga et al, 2016) showed that the number and position of secretory ducts can vary, rendering it difficult to use this character as the only parameter of differentiation among species.…”

“…This species is characterized by intraspecific structural variations and high degree of polymorphisms in color and shape of the leaf blade since its representatives are tolerant to different light intensities (Magenta and Pirani, 2014). Several taxonomic studies have been conducted on Brazilian Aldama species (Bombo et al, 2012(Bombo et al, , 2014Oliveira et al, 2013;Silva et al, 2014); however, such studies have addressed only the qualitative anatomical characters of these species, but not the quantitative traits.…”

Trichomes and chemical composition of the volatile oil of Trichogonia cinerea (Gardner) R. M. King & H. Rob. (Eupatorieae, Asteraceae)

“…The biseriate vesicular glandular trichomes of T. cinerea are similar to those found on the aerial organs of other Asteraceae species and several aspects of these structures have been investigated (Ascensão and Pais 1987, Figueiredo and Pais 1994, Afolayan and Meyer 1995, Pagni 1995, Castro et al 1997, Ascensão et al 2001, Heinrich et al 2002, Andreucci et al 2008, Oliveira et al 2013, Trindade et al 2014.…”

Seed germination of Brazilian Aldama species (Asteraceae)

“…Brazilian species from this genus occur mainly in the Cerrado regions in climates that have dry winters (Magenta et al, 2010), and these species are most often observed under such conditions that may be related to the type of thickened underground system, which supports the plants' water needs during dormancy (Zaidan and Carreira, 2008;Magenta et al, 2010) and is essential for regenerating the vegetative aerial portions (Oliveira et al, 2013;Bombo et al, 2014). The thickened underground systems, which can bear buds, were observed in other Asteraceae species, and these systems may be morphologically diverse, such as xylopodia, rhizophores, root buds and diffuse underground systems (Vilhalva and Appezzato-da-Glória, 2006;Hayashi and Appezzato-da-Glória, 2007;Appezzato-da-Glória et al, 2008;Appezzato-da-Glória and Cury, 2011).…”